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Monday, November 4, 2019

Cerebral palsy

From Wikipedia, the free encyclopedia
 
Cerebral palsy
USS Kearsarge medical team treat patients at Arima District Health Facility DVIDS126489.jpg
A child with cerebral palsy being assessed by a physician
SpecialtyPediatrics, neurology, physiatry
SymptomsPoor coordination, stiff muscles, weak muscles, tremors
ComplicationsSeizures, intellectual disability
Usual onsetEarly childhood
DurationLifelong
CausesOften unknown
Risk factorsPreterm birth, being a twin, certain infections during pregnancy, difficult delivery
Diagnostic methodBased on child's development
TreatmentPhysical therapy, occupational therapy, speech therapy, external braces, orthopedic surgery
MedicationDiazepam, baclofen, botulinum toxin
Frequency2.1 per 1,000

Cerebral palsy (CP) is a group of permanent movement disorders that appear in early childhood. Signs and symptoms vary among people and over time. Often, symptoms include poor coordination, stiff muscles, weak muscles, and tremors. There may be problems with sensation, vision, hearing, swallowing, and speaking. Often, babies with cerebral palsy do not roll over, sit, crawl or walk as early as other children of their age. Other symptoms include seizures and problems with thinking or reasoning, which each occur in about one third of people with CP. While symptoms may get more noticeable over the first few years of life, underlying problems do not worsen over time.

Cerebral palsy is caused by abnormal development or damage to the parts of the brain that control movement, balance, and posture. Most often, the problems occur during pregnancy; however, they may also occur during childbirth or shortly after birth. Often, the cause is unknown. Risk factors include preterm birth, being a twin, certain infections during pregnancy such as toxoplasmosis or rubella, exposure to methylmercury during pregnancy, a difficult delivery, and head trauma during the first few years of life, among others. About 2% of cases are believed to be due to an inherited genetic cause. A number of sub-types are classified based on the specific problems present. For example, those with stiff muscles have spastic cerebral palsy, those with poor coordination have ataxic cerebral palsy and those with writhing movements have athetoid cerebral palsy. Diagnosis is based on the child's development over time. Blood tests and medical imaging may be used to rule out other possible causes.

CP is partly preventable through immunization of the mother and efforts to prevent head injuries in children such as through improved safety. There is no known cure for CP; however, supportive treatments, medications and surgery may help many individuals. This may include physical therapy, occupational therapy and speech therapy. Medications such as diazepam, baclofen and botulinum toxin may help relax stiff muscles. Surgery may include lengthening muscles and cutting overly active nerves. Often, external braces and other assistive technology are helpful. Some affected children can achieve near normal adult lives with appropriate treatment. While alternative medicines are frequently used, there is no evidence to support their use.

Cerebral palsy is the most common movement disorder in children. It occurs in about 2.1 per 1,000 live births. Cerebral palsy has been documented throughout history, with the first known descriptions occurring in the work of Hippocrates in the 5th century BCE. Extensive study of the condition began in the 19th century by William John Little, after whom spastic diplegia was called "Little's disease". William Osler first named it "cerebral palsy" from the German zerebrale Kinderlähmung (cerebral child-paralysis). A number of potential treatments are being examined, including stem cell therapy. However, more research is required to determine if it is effective and safe.

Signs and symptoms

Cerebral palsy is defined as "a group of permanent disorders of the development of movement and posture, causing activity limitation, that are attributed to non-progressive disturbances that occurred in the developing fetal or infant brain." While movement problems are the central feature of CP, difficulties with thinking, learning, feeling, communication and behavior often co-occur, with 28% having epilepsy, 58% having difficulties with communication, at least 42% having problems with their vision, and 23–56% having learning disabilities. Muscle contractions in people with cerebral palsy are commonly thought to arise from overactivation.

Cerebral palsy is characterized by abnormal muscle tone, reflexes, or motor development and coordination. The neurological lesion is primary and permanent while orthopedic manifestations are secondary and progressive. In cerebral palsy unequal growth between muscle-tendon units and bone eventually leads to bone and joint deformities. At first deformities are dynamic. Over time, deformities tend to become static, and joint contractures develop. Deformities in general and static deformities in specific (joint contractures) cause increasing gait difficulties in the form of tip-toeing gait, due to tightness of the Achilles tendon, and scissoring gait, due to tightness of the hip adductors. These gait patterns are among the most common gait abnormalities in children with cerebral palsy. However, orthopaedic manifestations of cerebral palsy are diverse. The effects of cerebral palsy fall on a continuum of motor dysfunction, which may range from slight clumsiness at the mild end of the spectrum to impairments so severe that they render coordinated movement virtually impossible at the other end of the spectrum. Although most people with CP have problems with increased muscle tone, some have normal or low muscle tone. High muscle tone can either be due to spasticity or dystonia.

Babies born with severe cerebral palsy often have an irregular posture; their bodies may be either very floppy or very stiff. Birth defects, such as spinal curvature, a small jawbone, or a small head sometimes occur along with CP. Symptoms may appear or change as a child gets older. Babies born with cerebral palsy do not immediately present with symptoms. Classically, CP becomes evident when the baby reaches the developmental stage at 6 to 9 months and is starting to mobilise, where preferential use of limbs, asymmetry, or gross motor developmental delay is seen.

Drooling is common among children with cerebral palsy, which can have a variety of impacts including social rejection, impaired speaking, damage to clothing and books, and mouth infections. It can additionally cause choking.

An average of 55.5% of people with cerebral palsy experience lower urinary tract symptoms, more commonly excessive storage issues than voiding issues. Those with voiding issues and pelvic floor overactivity can deteriorate as adults and experience upper urinary tract dysfunction.

Children with CP may also have sensory processing issues. Adults with cerebral palsy have a higher risk of respiratory failure.

Skeleton

For bones to attain their normal shape and size, they require the stresses from normal musculature. People with cerebral palsy are at risk of low bone mineral density. The shafts of the bones are often thin (gracile), and become thinner during growth. When compared to these thin shafts (diaphyses), the centres (metaphyses) often appear quite enlarged (ballooning). Due to more than normal joint compression caused by muscular imbalances, articular cartilage may atrophy, leading to narrowed joint spaces. Depending on the degree of spasticity, a person with CP may exhibit a variety of angular joint deformities. Because vertebral bodies need vertical gravitational loading forces to develop properly, spasticity and an abnormal gait can hinder proper or full bone and skeletal development. People with CP tend to be shorter in height than the average person because their bones are not allowed to grow to their full potential. Sometimes bones grow to different lengths, so the person may have one leg longer than the other.

Children with CP are prone to low trauma fractures, particularly children with higher GMFCS levels who cannot walk. This further affects a child's mobility, strength, experience of pain, and can lead to missed schooling or child abuse suspicions. These children generally have fractures in the legs, whereas non-affected children mostly fracture their arms in the context of sporting activities.

Hip dislocation and ankle equinus or planter flexion deformity are the two most common deformities among children with cerebral palsy. Additionally, flexion deformity of the hip and knee can occur. Besides, torsional deformities of long bones such as the femur and tibia are encountered among others. Children may develop scoliosis before the age of 10 – estimated prevalence of scoliosis in children with CP is between 21% and 64%. Higher levels of impairment on the GMFCS are associated with scoliosis and hip dislocation. Scoliosis can be corrected with surgery, but CP makes surgical complications more likely, even with improved techniques. Hip migration can be managed by soft tissue procedures such as adductor musculature release. Advanced degrees of hip migration or dislocation can be managed by more extensive procedures such as femoral and pelvic corrective osteotomies. Both soft tissue and bony procedures aim at prevention of hip dislocation in the early phases or aim at hip containment and restoration of anatomy in the late phases of disease. Equinus deformity is managed by conservative methods especially when dynamic. If fixed/static deformity ensues surgery may become mandatory.

Growth spurts during puberty can make walking more difficult.

Eating

Due to sensory and motor impairments, those with CP may have difficulty preparing food, holding utensils, or chewing and swallowing. An infant with CP may not be able to suck, swallow or chew. Gastro-oesophageal reflux is common in children with CP. Children with CP may have too little or too much sensitivity around and in the mouth. Poor balance when sitting, lack of control of the head, mouth and trunk, not being able to bend the hips enough to allow the arms to stretch forward to reach and grasp food or utensils, and lack of hand-eye coordination can make self-feeding difficult. Feeding difficulties are related to higher GMFCS levels. Dental problems can also contribute to difficulties with eating. Pneumonia is also common where eating difficulties exist, caused by undetected aspiration of food or liquids. Fine finger dexterity, like that needed for picking up a utensil, is more frequently impaired than gross manual dexterity, like that needed for spooning food onto a plate. Grip strength impairments are less common.

Children with severe cerebral palsy, particularly with oropharyngeal issues, are at risk of undernutrition. Triceps skin fold tests have been found to be a very reliable indicator of malnutrition in children with cerebral palsy.

Language

Speech and language disorders are common in people with cerebral palsy. The incidence of dysarthria is estimated to range from 31% to 88%, and around a quarter of people with CP are non-verbal. Speech problems are associated with poor respiratory control, laryngeal and velopharyngeal dysfunction, and oral articulation disorders that are due to restricted movement in the oral-facial muscles. There are three major types of dysarthria in cerebral palsy: spastic, dyskinetic (athetosis), and ataxic.

Early use of augmentative and alternative communication systems may assist the child in developing spoken language skills. Overall language delay is associated with problems of cognition, deafness, and learned helplessness. Children with cerebral palsy are at risk of learned helplessness and becoming passive communicators, initiating little communication. Early intervention with this clientele, and their parents, often targets situations in which children communicate with others so that they learn that they can control people and objects in their environment through this communication, including making choices, decisions, and mistakes.

Pain and sleep

Pain is common and may result from the inherent deficits associated with the condition, along with the numerous procedures children typically face. When children with cerebral palsy are in pain, they experience worse muscle spasms. Pain is associated with tight or shortened muscles, abnormal posture, stiff joints, unsuitable orthosis, etc. Hip migration or dislocation is a recognizable source of pain in CP children and especially in the adolescent population. Nevertheless, the adequate scoring and scaling of pain in CP children remains challenging. Pain in CP has a number of different causes, and different pains respond to different treatments.

There is also a high likelihood of chronic sleep disorders secondary to both physical and environmental factors. Children with cerebral palsy have significantly higher rates of sleep disturbance than typically developing children. Babies with cerebral palsy who have stiffness issues might cry more and be harder to put to sleep than non-disabled babies, or "floppy" babies might be lethargic. Chronic pain is under-recognized in children with cerebral palsy, even though 3 out of 4 children with cerebral palsy experience pain.

Associated disorders

Associated disorders include intellectual disabilities, seizures, muscle contractures, abnormal gait, osteoporosis, communication disorders, malnutrition, sleep disorders, and mental health disorders, such as depression and anxiety. In addition to these, functional gastrointestinal abnormalities contributing to bowel obstruction, vomiting, and constipation may also arise. Adults with cerebral palsy may have ischemic heart disease, cerebrovascular disease, cancer, and trauma more often. Obesity in people with cerebral palsy or a more severe Gross Motor Function Classification System assessment in particular are considered risk factors for multimorbidity. Other medical issues can be mistaken for being symptoms of cerebral palsy, and so may not be treated correctly.

Related conditions can include apraxia, dysarthria or other communication disorders, sensory impairments, urinary incontinence, fecal incontinence, or behavioural disorders.

Seizure management is more difficult in people with CP as seizures often last longer.

The associated disorders that co-occur with cerebral palsy may be more disabling than the motor function problems.

Causes

refer to caption
Micrograph showing a fetal (placental) vein thrombosis, in a case of fetal thrombotic vasculopathy. This is associated with cerebral palsy and is suggestive of a hypercoagulable state as the underlying cause.
 
Cerebral palsy is due to abnormal development or damage occurring to the developing brain. This damage can occur during pregnancy, delivery, the first month of life, or less commonly in early childhood. Structural problems in the brain are seen in 80% of cases, most commonly within the white matter. More than three-quarters of cases are believed to result from issues that occur during pregnancy. Most children who are born with cerebral palsy have more than one risk factor associated with CP.

While in certain cases there is no identifiable cause, typical causes include problems in intrauterine development (e.g. exposure to radiation, infection, fetal growth restriction), hypoxia of the brain (thrombotic events, placental conditions), birth trauma during labor and delivery, and complications around birth or during childhood.

In Africa birth asphyxia, high bilirubin levels, and infections in newborns of the central nervous system are main cause. Many cases of CP in Africa could be prevented with better resources available.

Preterm birth

Between 40% and 50% of all children who develop cerebral palsy were born prematurely. Most of these cases (75-90%) are believed due to issues that occur around the time of birth, often just after birth. Multiple-birth infants are also more likely than single-birth infants to have CP. They are also more likely to be born with a low birth weight.

In those who are born with a weight between 1 kg and 1.5 kg CP occurs in 6%. Among those born before 28 weeks of gestation it occurs in 11%. Genetic factors are believed to play an important role in prematurity and cerebral palsy generally. While in those who are born between 34 and 37 weeks the risk is 0.4% (three times normal).

Term infants

In babies that are born at term risk factors include problems with the placenta, birth defects, low birth weight, breathing meconium into the lungs, a delivery requiring either the use of instruments or an emergency Caesarean section, birth asphyxia, seizures just after birth, respiratory distress syndrome, low blood sugar, and infections in the baby.

As of 2013, it was unclear how much of a role birth asphyxia plays as a cause. It is unclear if the size of the placenta plays a role. As of 2015 it is evident that in advanced countries, most cases of cerebral palsy in term or near-term neonates have explanations other than asphyxia.

Genetics

Autosomal recessive inheritance pattern.
 
About 2% of all CP cases are inherited, with glutamate decarboxylase-1 being one of the possible enzymes involved. Most inherited cases are autosomal recessive.

Early childhood

After birth, other causes include toxins, severe jaundice, lead poisoning, physical brain injury, stroke, abusive head trauma, incidents involving hypoxia to the brain (such as near drowning), and encephalitis or meningitis.

Others

Infections in the mother, even those not easily detected, can triple the risk of the child developing cerebral palsy. Infections of the fetal membranes known as chorioamnionitis increases the risk.

Intrauterine and neonatal insults (many of which are infectious) increase the risk.

It has been hypothesised that some cases of cerebral palsy are caused by the death in very early pregnancy of an identical twin.

Rh blood type incompatibility can cause the mother's immune system to attack the baby's red blood cells.

Diagnosis

The diagnosis of cerebral palsy has historically rested on the person's history and physical examination. A general movements assessment, which involves measuring movements that occur spontaneously among those less than four months of age, appears most accurate. Children who are more severely affected are more likely to be noticed and diagnosed earlier. Abnormal muscle tone, delayed motor development and persistence of primitive reflexes are the main early symptoms of CP. Symptoms and diagnosis typically occur by the age of 2, although persons with milder forms of cerebral palsy may be over the age of 5, if not in adulthood, when finally diagnosed. Early diagnosis and intervention are seen as being a key part of managing cerebral palsy. It is a developmental disability.

Once a person is diagnosed with cerebral palsy, further diagnostic tests are optional. Neuroimaging with CT or MRI is warranted when the cause of a person's cerebral palsy has not been established. An MRI is preferred over CT, due to diagnostic yield and safety. When abnormal, the neuroimaging study can suggest the timing of the initial damage. The CT or MRI is also capable of revealing treatable conditions, such as hydrocephalus, porencephaly, arteriovenous malformation, subdural hematomas and hygromas, and a vermian tumour (which a few studies suggest are present 5–22% of the time). Furthermore, an abnormal neuroimaging study indicates a high likelihood of associated conditions, such as epilepsy and intellectual disability. There is a small risk associated with sedating children in facilitate a clear MRI.

The age when CP is diagnosed is important, but medical professionals disagree over the best age to make the diagnosis. The earlier CP is diagnosed correctly, the better the opportunities are to provide the child with physical and educational help, but there might be a greater chance of confusing CP with another problem, especially if the child is 18 months of age or younger. Infants may have temporary problems with muscle tone or control that can be confused with CP, which is permanent. A metabolism disorder or tumors in the nervous system may appear to be CP; metabolic disorders, in particular, can produce brain problems that look like CP on an MRI. Disorders that deteriorate the white matter in the brain and problems that cause spasms and weakness in the legs, may be mistaken for CP if they first appear early in life. However, these disorders get worse over time, and CP does not (although it may change in character). In infancy it may not be possible to tell the difference between them. In the UK, not being able to sit independently by the age of 8 months is regarded as a clinical sign for further monitoring. Fragile X syndrome (a cause of autism and intellectual disability) and general intellectual disability must also be ruled out. Cerebral palsy specialist John McLaughlin recommends waiting until the child is 36 months of age before making a diagnosis, because by that age, motor capacity is easier to assess.

Classification

CP is classified by the types of motor impairment of the limbs or organs, and by restrictions to the activities an affected person may perform. The Gross Motor Function Classification System-Expanded and Revised and the Manual Ability Classification System are used to describe mobility and manual dexterity in people with cerebral palsy, and recently the Communication Function Classification System, and the Eating and Drinking Ability Classification System have been proposed to describe those functions. There are three main CP classifications by motor impairment: spastic, ataxic, and athetoid/dyskinetic. Additionally, there is a mixed type that shows a combination of features of the other types. These classifications reflect the areas of the brain that are damaged.

Cerebral palsy is also classified according to the topographic distribution of muscle spasticity. This method classifies children as diplegic, (bilateral involvement with leg involvement greater than arm involvement), hemiplegic (unilateral involvement), or quadriplegic (bilateral involvement with arm involvement equal to or greater than leg involvement).

Spastic

Spastic cerebral palsy, or cerebral palsy where spasticity (muscle tightness) is the exclusive or almost exclusive impairment present, is by far the most common type of overall cerebral palsy, occurring in upwards of 70% of all cases. People with this type of CP are hypertonic and have what is essentially a neuromuscular mobility impairment (rather than hypotonia or paralysis) stemming from an upper motor neuron lesion in the brain as well as the corticospinal tract or the motor cortex. This damage impairs the ability of some nerve receptors in the spine to receive gamma-Aminobutyric acid properly, leading to hypertonia in the muscles signaled by those damaged nerves.

As compared to other types of CP, and especially as compared to hypotonic or paralytic mobility disabilities, spastic CP is typically more easily manageable by the person affected, and medical treatment can be pursued on a multitude of orthopedic and neurological fronts throughout life. In any form of spastic CP, clonus of the affected limb(s) may sometimes result, as well as muscle spasms resulting from the pain or stress of the tightness experienced. The spasticity can and usually does lead to a very early onset of muscle stress symptoms like arthritis and tendinitis, especially in ambulatory individuals in their mid-20s and early-30s. Physical therapy and occupational therapy regimens of assisted stretching, strengthening, functional tasks, or targeted physical activity and exercise are usually the chief ways to keep spastic CP well-managed. If the spasticity is too much for the person to handle, other remedies may be considered, such as antispasmodic medications, botulinum toxin, baclofen, or even a neurosurgery known as a selective dorsal rhizotomy (which eliminates the spasticity by reducing the excitatory neural response in the nerves causing it).[citation needed] Botulinum toxin is effective in decreasing spasticity. It can help increase range of motion which could help mitigate CPs effects on the growing bones of children. There is an improvement in motor functions in the children and ability to walk.

Ataxic

Ataxic cerebral palsy is observed in approximately 5-10% of all cases of cerebral palsy, making it the least frequent form of cerebral palsy. Ataxic cerebral palsy is caused by damage to cerebellar structures. Because of the damage to the cerebellum, which is essential for coordinating muscle movements and balance, patients with ataxic cerebral palsy experience problems in coordination, specifically in their arms, legs, and trunk. Ataxic cerebral palsy is known to decrease muscle tone. The most common manifestation of ataxic cerebral palsy is intention (action) tremor, which is especially apparent when carrying out precise movements, such as tying shoe laces or writing with a pencil. This symptom gets progressively worse as the movement persists, making the hand shake. As the hand gets closer to accomplishing the intended task, the trembling intensifies, which makes it even more difficult to complete.

Athetoid

Athetoid cerebral palsy or dyskinetic cerebral palsy (sometimes abbreviated ADCP) is primarily associated with damage to the basal ganglia and the substantia nigra in the form of lesions that occur during brain development due to bilirubin encephalopathy and hypoxic-ischemic brain injury. ADCP is characterized by both hypertonia and hypotonia, due to the affected individual's inability to control muscle tone. Clinical diagnosis of ADCP typically occurs within 18 months of birth and is primarily based upon motor function and neuroimaging techniques. Athetoid dyskinetic cerebral palsy is a non-spastic, extrapyramidal form of cerebral palsy. Dyskinetic cerebral palsy can be divided into two different groups; choreoathetoid and dystonic. Choreo-athetotic CP is characterized by involuntary movements most predominantly found in the face and extremities. Dystonic ADCP is characterized by slow, strong contractions, which may occur locally or encompass the whole body.

Mixed

Mixed cerebral palsy has symptoms of athetoid, ataxic and spastic CP appearing simultaneously, each to varying degrees, and both with and without symptoms of each. Mixed CP is the most difficult to treat as it is extremely heterogeneous and sometimes unpredictable in its symptoms and development over the lifespan.

Prevention

Because the causes of CP are varied, a broad range of preventative interventions have been investigated.

Electronic fetal monitoring has not helped to prevent CP, and in 2014 the American College of Obstetricians and Gynecologists, the Royal Australian and New Zealand College of Obstetricians and Gynaecologists, and the Society of Obstetricians and Gynaecologists of Canada have acknowledged that there are no long-term benefits of electronic fetal monitoring. Prior to this, electronic fetal monitoring was widely used to prop up obstetric litigation.

In those at risk of an early delivery, magnesium sulphate appears to decrease the risk of cerebral palsy. It is unclear if it helps those who are born at term. In those at high risk of preterm labor a review found that moderate to severe CP was reduced by the administration of magnesium sulphate, and that adverse effects on the babies from the magnesium sulphate were not significant. Mothers who received magnesium sulphate could experience side effects such as respiratory depression and nausea. However, guidelines for the use of magnesium sulfate in mothers at risk of preterm labour are not strongly adhered to. Caffeine is used to treat apnea of prematurity and reduces the risk of cerebral palsy in premature babies, but there are also concerns of long term negative effects. A moderate quality level of evidence indicates that giving women antibiotics during preterm labor before her membranes have ruptured (water is not yet not broken) may increase the risk of cerebral palsy for the child. Additionally, for preterm babies for whom there is a chance of fetal compromise, allowing the birth to proceed rather than trying to delay the birth may lead to an increased risk of cerebral palsy in the child. Corticosteroids are sometimes taken by pregnant women expecting a preterm birth to provide neuroprotection to their baby. Taking corticosteroids during pregnancy is shown to have no significant correlation with developing cerebral palsy in preterm births.

Cooling high-risk full-term babies shortly after birth may reduce disability, but this may only be useful for some forms of the brain damage that causes CP.

Management

A girl wearing leg braces walks towards a woman in a gym, with a treadmill visible in the background.
Researchers are developing an electrical stimulation device specifically for children with cerebral palsy, who have foot drop, which causes tripping when walking.


Over time, the approach to CP management has shifted away from narrow attempts to fix individual physical problems – such as spasticity in a particular limb – to making such treatments part of a larger goal of maximizing the person's independence and community engagement. Much of childhood therapy is aimed at improving gait and walking. Approximately 60% of people with CP are able to walk independently or with aids at adulthood. However, the evidence base for the effectiveness of intervention programs reflecting the philosophy of independence has not yet caught up: effective interventions for body structures and functions have a strong evidence base, but evidence is lacking for effective interventions targeted toward participation, environment, or personal factors. There is also no good evidence to show that an intervention that is effective at the body-specific level will result in an improvement at the activity level, or vice versa. Although such cross-over benefit might happen, not enough high-quality studies have been done to demonstrate it.

Because cerebral palsy has "varying severity and complexity" across the lifespan, it can be considered a collection of conditions for management purposes. A multidisciplinary approach for cerebral palsy management is recommended, focusing on "maximising individual function, choice and independence" in line with the International Classification of Functioning, Disability and Health's goals. The team may include a paediatrician, a health visitor, a social worker, a physiotherapist, an orthotist, a speech and language therapist, an occupational therapist, a teacher specialising in helping children with visual impairment, an educational psychologist, an orthopaedic surgeon, a neurologist and a neurosurgeon.

Various forms of therapy are available to people living with cerebral palsy as well as caregivers and parents. Treatment may include one or more of the following: physical therapy; occupational therapy; speech therapy; water therapy; drugs to control seizures, alleviate pain, or relax muscle spasms (e.g. benzodiazepines); surgery to correct anatomical abnormalities or release tight muscles; braces and other orthotic devices; rolling walkers; and communication aids such as computers with attached voice synthesisers. A Cochrane review published in 2004 found a trend toward benefit of speech and language therapy for children with cerebral palsy, but noted the need for high quality research. A 2013 systematic review found that many of the therapies used to treat CP have no good evidence base; the treatments with the best evidence are medications (anticonvulsants, botulinum toxin, bisphosphonates, diazepam), therapy (bimanual training, casting, constraint-induced movement therapy, context-focused therapy, fitness training, goal-directed training, hip surveillance, home programmes, occupational therapy after botulinum toxin, pressure care) and surgery. Surgical intervention in CP children mainly includes orthopaedic surgery and neurosurgery (selective dorsal rhizotomy).

Prognosis

CP is not a progressive disorder (meaning the brain damage does not worsen), but the symptoms can become more severe over time. A person with the disorder may improve somewhat during childhood if he or she receives extensive care, but once bones and musculature become more established, orthopedic surgery may be required. People with CP can have varying degrees of cognitive impairment or none whatsoever. The full intellectual potential of a child born with CP is often not known until the child starts school. People with CP are more likely to have learning disorders, but have normal intelligence. Intellectual level among people with CP varies from genius to intellectually disabled, as it does in the general population, and experts have stated that it is important not to underestimate the capabilities of a person with CP and to give them every opportunity to learn.

The ability to live independently with CP varies widely, depending partly on the severity of each person's impairment and partly on the capability of each person to self-manage the logistics of life. Some individuals with CP require personal assistant services for all activities of daily living. Others only need assistance with certain activities, and still others do not require any physical assistance. But regardless of the severity of a person's physical impairment, a person's ability to live independently often depends primarily on the person's capacity to manage the physical realities of his or her life autonomously. In some cases, people with CP recruit, hire, and manage a staff of personal care assistants (PCAs). PCAs facilitate the independence of their employers by assisting them with their daily personal needs in a way that allows them to maintain control over their lives.

Puberty in young adults with cerebral palsy may be precocious or delayed. Delayed puberty is thought to be a consequence of nutritional deficiencies. There is currently no evidence that CP affects fertility, although some of the secondary symptoms have been shown to affect sexual desire and performance. Adults with CP were less likely to get routine reproductive health screening as of 2005. Gynecological examinations may have to be performed under anesthesia due to spasticity, and equipment is often not accessible. Breast self-examination may be difficult, so partners or carers may have to perform it. Women with CP reported higher levels of spasticity and urinary incontinence during menstruation in a study. Men with CP have higher levels of cryptorchidism at the age of 21.

CP can significantly reduce a person's life expectancy, depending on the severity of their condition and the quality of care they receive. 5-10% of children with CP die in childhood, particularly where seizures and intellectual disability also affect the child. The ability to ambulate, roll, and self-feed has been associated with increased life expectancy. While there is a lot of variation in how CP affects people, it has been found that "independent gross motor functional ability is a very strong determinant of life expectancy". According to the Australian Bureau of Statistics, in 2014, 104 Australians died of cerebral palsy. The most common causes of death in CP are related to respiratory causes, but in middle age cardiovascular issues and neoplastic disorders become more prominent.

Self-care

For many children with CP, parents are heavily involved in self-care activities. Self-care activities, such as bathing, dressing, grooming, can be difficult for children with CP as self-care depends primarily on use of the upper limbs. For those living with CP, impaired upper limb function affects almost 50% of children and is considered the main factor contributing to decreased activity and participation. As the hands are used for many self-care tasks, sensory and motor impairments of the hands make daily self-care more difficult. Motor impairments cause more problems than sensory impairments. The most common impairment is that of finger dexterity, which is the ability to manipulate small objects with the fingers. Compared to other disabilities, people with cerebral palsy generally need more help in performing daily tasks. Occupational therapists are healthcare professionals that help individuals with disabilities gain or regain their independence through the use of meaningful activities.

Productivity

The effects of sensory, motor and cognitive impairments affect self-care occupations in children with CP and productivity occupations. Productivity can include, but is not limited to, school, work, household chores or contributing to the community.

Play is included as a productive occupation as it is often the primary activity for children. If play becomes difficult due to a disability, like CP, this can cause problems for the child. These difficulties can affect a child's self-esteem. In addition, the sensory and motor problems experienced by children with CP affect how the child interacts with their surroundings, including the environment and other people. Not only do physical limitations affect a child's ability to play, the limitations perceived by the child's caregivers and playmates also affect the child's play activities. Some children with disabilities spend more time playing by themselves. When a disability prevents a child from playing, there may be social, emotional and psychological problems, which can lead to increased dependence on others, less motivation, and poor social skills.

In school, students are asked to complete many tasks and activities, many of which involve handwriting. Many children with CP have the capacity to learn and write in the school environment. However, students with CP may find it difficult to keep up with the handwriting demands of school and their writing may be difficult to read. In addition, writing may take longer and require greater effort on the student's part. Factors linked to handwriting include postural stability, sensory and perceptual abilities of the hand, and writing tool pressure.

Speech impairments may be seen in children with CP depending on the severity of brain damage. Communication in a school setting is important because communicating with peers and teachers is very much a part of the "school experience" and enhances social interaction. Problems with language or motor dysfunction can lead to underestimating a student's intelligence. In summary, children with CP may experience difficulties in school, such as difficulty with handwriting, carrying out school activities, communicating verbally and interacting socially.

Leisure

Leisure activities can have several positive effects on physical health, mental health, life satisfaction and psychological growth for people with physical disabilities like CP. Common benefits identified are stress reduction, development of coping skills, companionship, enjoyment, relaxation and a positive effect on life satisfaction. In addition, for children with CP, leisure appears to enhance adjustment to living with a disability.

Leisure can be divided into structured (formal) and unstructured (informal) activities. Children and teens with CP engage in less habitual physical activity than their peers. Children with CP primarily engage in physical activity through therapies aimed at managing their CP, or through organized sport for people with disabilities. It is difficult to sustain behavioural change in terms of increasing physical activity of children with CP. Gender, manual dexterity, the child's preferences, cognitive impairment and epilepsy were found to affect children's leisure activities, with manual dexterity associated with more leisure activity. Although leisure is important for children with CP, they may have difficulties carrying out leisure activities due to social and physical barriers.

Children with cerebral palsy may face challenges when it comes to participating in sports. This comes with being discouraged from physical activity because of these perceived limitations imposed by their medical condition.

Participation and barriers

Participation is involvement in life situations and everyday activities. Participation includes self-care, productivity, and leisure. In fact, communication, mobility, education, home life, leisure and social relationships require participation, and indicate the extent to which children function in their environment. Barriers can exist on three levels: micro, meso and macro. First, the barriers at the micro level involve the person. Barriers at the micro level include the child's physical limitations (motor, sensory and cognitive impairments) or their subjective feelings regarding their ability to participate. For example, the child may not participate in group activities due to lack of confidence. Second, barriers at the meso level include the family and community. These may include negative attitudes of people toward disability or lack of support within the family or in the community. One of the main reasons for this limited support appears to be the result of a lack of awareness and knowledge regarding the child's ability to engage in activities despite his or her disability. Third, barriers at the macro level incorporate the systems and policies that are not in place or hinder children with CP. These may be environmental barriers to participation such as architectural barriers, lack of relevant assistive technology and transportation difficulties due to limited wheelchair access or public transit that can accommodate children with CP. For example, a building without an elevator can prevent the child from accessing higher floors. 

A 2013 review stated that outcomes for adults with cerebral palsy without intellectual disability in the 2000s were that "60-80% completed high school, 14-25% completed college, up to 61% were living independently in the community, 25-55% were competitively employed, and 14-28% were involved in long term relationships with partners or had established families". Adults with cerebral palsy may not seek physical therapy due to transport issues, financial restrictions and practitioners not feeling like they know enough about cerebral palsy to take people with CP on as clients.

A study in young adults (18-34) on transitioning to adulthood found that their concerns were physical health care and understanding their bodies, being able to navigate and use services and supports successfully, and dealing with prejudices. A feeling of being "thrust into adulthood" was common in the study.

Aging

Children with CP may not successfully transition into using adult services because they are not referred to one upon turning 18, and may decrease their use of services. Because children with cerebral palsy are often told that it is a non-progressive disease, they may be unprepared for the greater effects of the aging process as they head into their 30s. Young adults with cerebral palsy experience problems with aging that able-bodied adults experience "much later in life". 25% or more adults with cerebral palsy who can walk experience increasing difficulties walking with age. Chronic disease risk, such as obesity, is also higher among adults with cerebral palsy than the general population. Common problems include increased pain, reduced flexibility, increased spasms and contractures, post-impairment syndrome, and increasing problems with balance. Increased fatigue is also a problem. When adulthood and cerebral palsy is discussed, as of 2011, it is not discussed in terms of the different stages of adulthood.

Like they did in childhood, adults with cerebral palsy experience psychosocial issues related to their CP, chiefly the need for social support, self-acceptance, and acceptance by others. Workplace accommodations may be needed to enhance continued employment for adults with CP as they age. Rehabilitation or social programs that include salutogenesis may improve the coping potential of adults with CP as they age.

Epidemiology

Cerebral palsy occurs in about 2.1 per 1000 live births. In those born at term rates are lower at 1 per 1000 live births. Rates appear to be similar in both the developing and developed world. Within a population it may occur more often in poorer people. The rate is higher in males than in females; in Europe it is 1.3 times more common in males. Variances in reported rates of incidence or prevalence across different geographical areas in industrialised countries are thought to be caused primarily by discrepancies in the criteria used for inclusion and exclusion. When such discrepancies are accounted for in comparing two or more registers of patients with cerebral palsy (for example, the extent to which children with mild cerebral palsy are included), prevalence rates converge toward the average rate of 2:1000.

There was a "moderate, but significant" rise in the prevalence of CP between the 1970s and 1990s. This is thought to be due to a rise in low birth weight of infants and the increased survival rate of these infants. The increased survival rate of infants with CP in the 1970s and 80s may be indirectly due to the disability rights movement challenging perspectives around the worth of infants with disability, as well as the Baby Doe Law.

As of 2005, advances in care of pregnant mothers and their babies has not resulted in a noticeable decrease in CP. This is generally attributed to medical advances in areas related to the care of premature babies (which results in a greater survival rate). Only the introduction of quality medical care to locations with less-than-adequate medical care has shown any decreases. The incidence of CP increases with premature or very low-weight babies regardless of the quality of care. As of 2016, there is a suggestion that both incidence and severity are slightly decreasing - more research is needed to find out if this is significant, and if so, which interventions are effective.

Prevalence of cerebral palsy is best calculated around the school entry age of about 6 years, the prevalence in the U.S. is estimated to be 2.4 out of 1000 children.

History

Cerebral palsy has affected humans since antiquity. A decorated grave marker dating from around the 15th to 14th century BCE shows a figure with one small leg and using a crutch, possibly due to cerebral palsy. The oldest likely physical evidence of the condition comes from the mummy of Siptah, an Egyptian Pharaoh who ruled from about 1196 to 1190 BCE and died at about 20 years of age. The presence of cerebral palsy has been suspected due to his deformed foot and hands.

The medical literature of the ancient Greeks discusses paralysis and weakness of the arms and legs; the modern word palsy comes from the Ancient Greek words παράλυση or πάρεση, meaning paralysis or paresis respectively. The works of the school of Hippocrates (460–c. 370 BCE), and the manuscript On the Sacred Disease in particular, describe a group of problems that matches up very well with the modern understanding of cerebral palsy. The Roman Emperor Claudius (10 BCE–54 CE) is suspected of having CP, as historical records describe him as having several physical problems in line with the condition. Medical historians have begun to suspect and find depictions of CP in much later art. Several paintings from the 16th century and later show individuals with problems consistent with it, such as Jusepe de Ribera's 1642 painting The Clubfoot.

The modern understanding of CP as resulting from problems within the brain began in the early decades of the 1800s with a number of publications on brain abnormalities by Johann Christian Reil, Claude François Lallemand and Philippe Pinel. Later physicians used this research to connect problems in the brain with specific symptoms. The English surgeon William John Little (1810–1894) was the first person to study CP extensively. In his doctoral thesis he stated that CP was a result of a problem around the time of birth. He later identified a difficult delivery, a preterm birth and perinatal asphyxia in particular as risk factors. The spastic diplegia form of CP came to be known as Little's disease. At around this time, a German surgeon was also working on cerebral palsy, and distinguished it from polio. In the 1880s British neurologist William Gowers built on Little's work by linking paralysis in newborns to difficult births. He named the problem "birth palsy" and classified birth palsies into two types: peripheral and cerebral.

Working in Pennsylvania in the 1880s, Canadian-born physician William Osler (1849–1919) reviewed dozens of CP cases to further classify the disorders by the site of the problems on the body and by the underlying cause. Osler made further observations tying problems around the time of delivery with CP, and concluded that problems causing bleeding inside the brain were likely the root cause. Osler also suspected polioencephalitis as an infectious cause. Through the 1890s, scientists commonly confused CP with polio.

Before moving to psychiatry, Austrian neurologist Sigmund Freud (1856–1939) made further refinements to the classification of the disorder. He produced the system still being used today. Freud's system divides the causes of the disorder into problems present at birth, problems that develop during birth, and problems after birth. Freud also made a rough correlation between the location of the problem inside the brain and the location of the affected limbs on the body, and documented the many kinds of movement disorders.

In the early 20th century, the attention of the medical community generally turned away from CP until orthopedic surgeon Winthrop Phelps became the first physician to treat the disorder. He viewed CP from a musculoskeletal perspective instead of a neurological one. Phelps developed surgical techniques for operating on the muscles to address issues such as spasticity and muscle rigidity. Hungarian physical rehabilitation practitioner András Pető developed a system to teach children with CP how to walk and perform other basic movements. Pető's system became the foundation for conductive education, widely used for children with CP today. Through the remaining decades, physical therapy for CP has evolved, and has become a core component of the CP management program.

In 1997, Robert Palisano et al. introduced the Gross Motor Function Classification System (GMFCS) as an improvement over the previous rough assessment of limitation as either mild, moderate or severe. The GMFCS grades limitation based on observed proficiency in specific basic mobility skills such as sitting, standing and walking, and takes into account the level of dependency on aids such as wheelchairs or walkers. The GMFCS was further revised and expanded in 2007.

Society and culture

Economic impact

It is difficult to directly compare the cost and cost-effectiveness of interventions to prevent cerebral palsy or the cost of interventions to manage CP. Access Economics has released a report on the economic impact of cerebral palsy in Australia. The report found that, in 2007, the financial cost of cerebral palsy (CP) in Australia was $AUS 1.47 billion or 0.14% of GDP. Of this:
  • $AUS 1.03 billion (69.9%) was productivity lost due to lower employment, absenteeism and premature death of Australians with CP
  • $AUS 141 million (9.6%) was the DWL from transfers including welfare payments and taxation forgone
  • $AUS 131 million (9.0%) was other indirect costs such as direct program services, aides and home modifications and the bringing-forward of funeral costs
  • $AUS 129 million (8.8%) was the value of the informal care for people with CP
  • $AUS 40 million (2.8%) was direct health system expenditure
The value of lost well-being (disability and premature death) was a further $AUS 2.4 billion. 

In per capita terms, this amounts to a financial cost of $AUS 43,431 per person with CP per annum. Including the value of lost well-being, the cost is over $115,000 per person per annum.

Individuals with CP bear 37% of the financial costs, and their families and friends bear a further 6%. Federal government bears around one-third (33%) of the financial costs (mainly through taxation revenues forgone and welfare payments). State governments bear under 1% of the costs, while employers bear 5% and the rest of society bears the remaining 19%. If the burden of disease (lost well-being) is included, individuals bear 76% of the costs.

The average lifetime cost for people with CP in the US is $US921,000 per individual, including lost income.

In the United States many states allow Medicaid beneficiaries to use their Medicaid funds to hire their own PCAs, instead of forcing them to use institutional or managed care.

In India, the government-sponsored program called "NIRAMAYA" for the medical care of children with neurological and muscular deformities has proved to be an ameliorating economic measure for persons with such disabilities. It has shown that persons with mental or physically debilitating congenital disabilities can lead better lives if they have financial independence.

Use of the term

"Cerebral" means "of, or pertaining to, the cerebrum or the brain" and "palsy" means "paralysis, generally partial, whereby a local body area is incapable of voluntary movement". It has been proposed to change the name to "cerebral palsy spectrum disorder" to reflect the diversity of presentations of CP.

The term palsy in modern language refers to a disorder of movement, but the word root "palsy" technically means "paralysis", even though it is not used as such within the meaning of cerebral palsy. The use of "palsy" in the term cerebral palsy makes it important to note that paralytic disorders are in fact not cerebral palsy – meaning that the condition of tetraplegia, which comes from spinal cord injury or traumatic brain injury, should not be confused with spastic quadriplegia, which does not, nor should tardive dyskinesia be confused with dyskinetic cerebral palsy or the condition of (paralytic) "diplegia" with spastic diplegia. In fact, as of the early 21st century some clinicians have become so distressed at common incorrect use of these terms that they have resorted to new naming schemes rather than trying to reclaim the classic ones; one such example of this evolution is the increasing use of the term bilateral spasticity to refer to spastic diplegia. Such clinicians even argue quite often that the "new" term is technically more clinically accurate than the established term.

Many people would rather be referred to as a person with a disability (people-first language) instead of as handicapped. "Cerebral Palsy: A Guide for Care" at the University of Delaware offers the following guidelines:
Impairment is the correct term to use to define a deviation from normal, such as not being able to make a muscle move or not being able to control an unwanted movement. Disability is the term used to define a restriction in the ability to perform a normal activity of daily living which someone of the same age is able to perform. For example, a three-year-old child who is not able to walk has a disability because a normal three-year-old can walk independently. A handicapped child or adult is one who, because of the disability, is unable to achieve the normal role in society commensurate with his age and socio-cultural milieu. As an example, a sixteen-year-old who is unable to prepare his own meal or care for his own toilet or hygiene needs is handicapped. On the other hand, a sixteen-year-old who can walk only with the assistance of crutches but who attends a regular school and is fully independent in activities of daily living is disabled but not handicapped. All disabled people are impaired, and all handicapped people are disabled, but a person can be impaired and not necessarily be disabled, and a person can be disabled without being handicapped.
The term "spastic" denotes the attribute of spasticity in types of spastic CP. In 1952 a UK charity called The Spastics Society was formed. The term "spastics" was used by the charity as a term for people with CP. The word "spastic" has since been used extensively as a general insult to disabled people, which some see as extremely offensive. They are also frequently used to insult able-bodied people when they seem overly uncoordinated, anxious, or unskilled in sports. The charity changed its name to Scope in 1994. In the United States the word spaz has the same usage as an insult, but is not generally associated with CP.

Media

Maverick documentary filmmaker Kazuo Hara criticises the mores and customs of Japanese society in an unsentimental portrait of adults with cerebral palsy in his 1972 film Goodbye CP (Sayonara CP). Focusing on how people with cerebral palsy are generally ignored or disregarded in Japan, Hara challenges his society's taboos about physical handicaps. Using a deliberately harsh style, with grainy black-and-white photography and out-of-sync sound, Hara brings a stark realism to his subject.

Spandan (2012), a film by Vegitha Reddy and Aman Tripathi, delves into the dilemma of parents whose child has cerebral palsy. While films made with children with special needs as central characters have been attempted before, the predicament of parents dealing with the stigma associated with the condition and beyond is dealt in Spandan. In one of the songs of Spandan "Chal chaal chaal tu bala" more than 50 CP kids have acted. The famous classical singer Devaki Pandit has given her voice to the song penned by Prof. Jayant Dhupkar and composed by National Film Awards winner Isaac Thomas Kottukapally.

My Left Foot (1989) is a drama film directed by Jim Sheridan and starring Daniel Day-Lewis. It tells the true story of Christy Brown, an Irishman born with cerebral palsy, who could control only his left foot. Christy Brown grew up in a poor, working-class family, and became a writer and artist. It won the Academy Award for Best Actor (Daniel Day-Lewis) and Best Actress in a Supporting Role (Brenda Fricker). It was also nominated for Best Director, Best Picture and Best Writing, Screenplay Based on Material from Another Medium. It also won the New York Film Critics Circle Award for Best Film for 1989.

Call the Midwife (2012–) has featured two episodes with actor Colin Young, who he himself has cerebral palsy, playing a character with the same disability. His story lines have focused on the segregation of those with disabilities in the UK in the 1950s, and also romantic relationships between people with disabilities.

Micah Fowler, an American actor with CP, stars in the ABC sitcom Speechless (2016–), which explores both the serious and humorous challenges a family faces with a teenager with CP.

Special (2019) is a comedy series that premiered on Netflix on 12 April 2019. It was written, produced and stars Ryan O'Connell as a young gay man with mild cerebral palsy. It is based on O'Connell's book I'm Special: And Other Lies We Tell Ourselves.

Notable cases

Litigation

Because of the false perception that cerebral palsy is mostly caused by trauma during birth, as of 2005, 60% of obstetric litigation was about cerebral palsy, which Alastair MacLennan, Professor of Obstetrics and Gynaecology at the University of Adelaide, regards as causing an exodus from the profession. In the latter half of the 20th century, obstetric litigation about the cause of cerebral palsy became more common, leading to defensive medicine being practiced.

Genealogical DNA test

From Wikipedia, the free encyclopedia

A genealogical DNA test is a DNA-based test which looks at specific locations of a person's genome, in order to find or verify ancestral genealogical relationships or (with lower reliability) to estimate the ethnic mixture of an individual. Since different testing companies use different ethnic reference groups and different matching algorithms, ethnicity estimates for an individual will vary between tests, sometimes dramatically.

Three principal types of genealogical DNA tests are available, with each looking at a different part of the genome and useful for different types of genealogical research: autosomal, mitochondrial (mtDNA), and Y-DNA.

Autosomal tests may result in a large amount of DNA matches (other test persons that the individual may be related to), along mixed male and female lines, each match with an estimated distance in the family tree. However, due to the random nature of which and how much DNA is inherited by each tested person from their common ancestors, precise conclusions can only be made for close relations. Traditional genealogical research, and the sharing of family trees, is typically required for interpretation of the results. Autosomal tests are also used in estimating ethnic mix.

MtDNA and Y-DNA tests are much more objective. However, they give considerably fewer DNA matches, if any, since they are limited to relationships along a strict female line and a strict male line respectively. MtDNA and Y-DNA tests are utilized to identify archeological cultures and migration paths of a person's ancestors along a strict mother's line or a strict father's line. Based on MtDNA and Y-DNA, a person's haplogroup(s) can be identified. Only men can take Y-DNA tests, since women lack a Y chromosome.

DNA testing for consumers

The first company to provide direct-to-consumer genetic DNA testing was the now defunct GeneTree. However, it did not offer multi-generational genealogy tests. In fall 2001, GeneTree sold its assets to Salt Lake City-based Sorenson Molecular Genealogy Foundation (SMGF) which originated in 1999. While in operation, SMGF provided free Y-Chromosome and mitochondrial DNA tests to thousands. Later, GeneTree returned to genetic testing for genealogy in conjunction with the Sorenson parent company and eventually was part of the assets acquired in the Ancestry.com buyout of SMGF in 2012.

In 2000, Family Tree DNA, founded by Bennett Greenspan and Max Blankfeld, was the first company dedicated to direct-to-consumer testing for genealogy research. They initially offered eleven marker Y-Chromosome STR tests and HVR1 mitochondrial DNA tests. They originally tested in partnership with the University of Arizona.

In 2007, 23andMe was the first company to offer a saliva-based direct-to-consumer genetic testing. It was also the first to implement using autosomal DNA for ancestry testing, which all other major companies now use.

MyHeritage launched its genetic testing service in 2016, allowing users to use cheek swabs to collect samples. In 2019, new analysis tools were presented: autoclusters (grouping all matches visually into clusters) and family tree theories (suggesting conceivable relations between DNA matches by combining several Myheritage trees as well as the Geni global family tree).

Living DNA, founded in 2015, also provides a genetic testing service. Living DNA uses SNP chips to provide reports on autosomal ancestry, Y, and mtDNA ancestry. Living DNA provides detailed reports on ancestry from the UK as well as detailed Y chromosome and mtDNA reports.

In 2019 it was estimated that large genealogical testing companies had about 26 million DNA profiles. Many transferred their test result for free to multiple testing sites, and also to genealogical services such as Geni.com and GEDmatch. GEDMatch said half of their profiles were from the USA.
The popular consciousness of DNA testing and of DNA generally is subject to a number of misconceptions involving the reliability of testing, the nature of the connections with one's ancestors, the connection between DNA and personal traits, etc.

Procedure

A hospital corpsman uses a swab to take a DNA sample from a sailor aboard USS Iwo Jima (LHD 7)
 
A genealogical DNA test is performed on a DNA sample. This DNA sample can be obtained by a cheek-scraping (also known as a buccal swab), spit-cups, mouthwash, and chewing gum. Typically, the sample collection uses a home test kit supplied by a service provider such as 23andMe, AncestryDNA, Family Tree DNA, or MyHeritage. After following the kit instructions on how to collect the sample, it is returned to the supplier for analysis.

Types of tests

There are three major types of genealogical DNA tests: Autosomal and X-DNA, Y-DNA and mtDNA.
  • Autosomal tests look at chromosomes 1–22 and X. The autosomes (chromosomes 1–22) are inherited from both parents and all recent ancestors. The X-chromosome follows a special inheritance pattern. Ethnicity estimates are often included with this sort of testing.
  • Y-DNA looks at the Y-chromosome, which is inherited father to son, and so can only be taken by males to explore their direct paternal line.
  • mtDNA looks at the mitochondria, which is inherited from mother to child and so can be used to explore one's direct maternal line.
Y-DNA and mtDNA cannot be used for ethnicity estimates, but can be used to find one's haplogroup, which is unevenly distributed geographically. Direct-to-consumer DNA test companies have often labeled haplogroups by continent or ethnicity (e.g., an "African haplogroup" or a "Viking haplogroup"), but these labels may be speculative or misleading.

Autosomal DNA (atDNA) testing

Testing

Autosomal DNA is contained in the 22 pairs of chromosomes not involved in determining a person's sex. Autosomal DNA recombines each generation, and new offspring receive one set of chromosomes from each parent. These are inherited exactly equally from both parents and roughly equally from grandparents to about 3x great-grand parents. Therefore, the number of markers (one of two or more known variants in the genome at a particular location – known as Single-nucleotide polymorphisms or SNPs) inherited from a specific ancestor decreases by about half each generation; that is, an individual receives half of their markers from each parent, about a quarter of their markers from each grandparent; about an eighth of their markers from each great grandparent, etc. Inheritance is more random and unequal from more distant ancestors. Generally, a genealogical DNA test might test about 700,000 SNPs (specific points in the genome).

Shared DNA for different relatives

Reporting process

The preparation of a report on the DNA in the sample proceeds in multiple stages:
  • identification of the DNA base pair at specific SNP locations
  • comparison with previously stored results
  • interpretation of matches
Base pair identification
All major service providers use equipment with chips supplied by Illumina. The chip determines which SNP locations are tested. Different versions of the chip are used by different service providers. In addition, updated versions of the Illumina chip may test different sets of SNP locations. The list of SNP locations and base pairs at that location is usually available to the customer as "raw data". The raw data can sometimes be uploaded to another service provider to produce an additional interpretation and matches. For additional analysis the data can also be uploaded to GEDmatch (a third-party web based set of tools that analyzes raw data from the main service providers).
Identification of Matches
The major component of an autosomal DNA test is matching other individuals. Where the individual being tested has a number of consecutive SNPs in common with a previously tested individual in the company's database, it can be inferred that they share a segment of DNA at that part of their genomes. If the segment is longer than a threshold amount set by the testing company, then these two individuals are considered to be a match. Unlike the identification of base pairs, the data bases against which the new sample is tested, and the algorithms used to determine a match, are proprietary and specific to each company.

The unit for segments of DNA is the centimorgan (cM). For comparison, a full human genome is about 6500 cM. The shorter the length of a match, the greater are the chances that a match is spurious. An important statistic for subsequent interpretation is the length of the shared DNA (or the percentage of the genome that is shared).
Interpretation of Autosomal matches
Most companies will show the customers how many cMs they share, and across how many segments. From the number of cMs and segments, the relationship between the two individuals can be estimated, however due to the random nature of DNA inheritance, relationship estimates, especially for distant relatives, are only approximate. Some more distant cousins will not match at all. Although information about specific SNPs can be used for some purposes (eg suggesting likely eye colour), the key information is the percentage of DNA shared by 2 individuals. This can indicate the closeness of the relationship. However, it does not show the roles of the 2 individuals - eg 50% shared suggests a parent - child relationship, but does not identify which individual is the parent. 

Various advanced techniques and analysis can be done on this data. This includes features such as In-common/Shared Matches, Chromosome Browsers and Triangulation. This analysis is often required if DNA evidence is being used to prove or disprove a specific relationship.

X-chromosome DNA testing

The X-chromosome SNP results are often included in Autosomal DNA tests. Both males and females receive an X-chromosome from their mother, but only females receive a second X-chromosome from their father. The X-chromosome has a special path of inheritance patterns and can be useful in significantly narrowing down possible ancestor lines compared to Autosomal DNA – for example an X-chromosome match with a male can only have come from his maternal side. Like autosomal DNA, X-chromosome DNA undergoes random recombination at each generation (except for father to daughter X-chromosomes which are passed down unchanged). There are specialised inheritance charts which describe the possible patterns of X-chromosome DNA inheritance for males and females.

STRs

Some genealogical companies offered autosomal STRs (short tandem repeats). These are similar to Y-DNA STRs. The number of STRs offered is limited, and results have been used for personal identification, paternity cases and inter-population studies.

Law enforcement agencies in the US and Europe use autosomal STR data to identify criminals.

Mitochondrial DNA (mtDNA) testing

The mitochondrion is a component of a human cell, and contains its own DNA. Mitochondrial DNA usually has 16,569 base pairs (the number can vary slightly depending on addition or deletion mutations) and is much smaller than the human genome DNA which has 3.2 billion base pairs. Mitochondrial DNA is transmitted from mother to child, thus a direct maternal ancestor can be traced using mtDNA. The transmission occurs with relatively rare mutations compared to the genome DNA. A perfect match found to another person's mtDNA test results indicates shared ancestry of possibly between 1 and 50 generations ago. More distant matching to a specific haplogroup or subclade may be linked to a common geographic origin.

Test

mtDNA, by current conventions, is divided into three regions. They are the coding region (00577-16023) and two Hyper Variable Regions (HVR1 [16024-16569], and HVR2 [00001-00576]).

The two most common mtDNA tests are a sequence of HVR1 and HVR2 and a full sequence of the mitochondria. Generally, testing only the HVRs has limited genealogical use so it is increasingly popular and accessible to have a full sequence. The full mtDNA sequence is only offered by Family Tree DNA among the major testing companies and is somewhat controversial because the coding region DNA may reveal medical information about the test-taker.

Haplogroups

Map of human migration out of Africa, according to Mitochondrial DNA. The numbers represent thousands of years before present time. The blue line represents the area covered in ice or tundra during the last great ice age. The North Pole is at the center. Africa, the center of the start of the migration, is at the top left and South America is at the far right.
 
All humans descend in the direct female line from Mitochondrial Eve, a female who lived probably around 200,000 years ago in Africa. Different branches of her descendants are different haplogroups. Most mtDNA results include a prediction or exact assertion of one's mtDNA Haplogroup. Mitochrondial haplogroups were greatly popularized by the book The Seven Daughters of Eve, which explores mitochondrial DNA.

Understanding mtDNA test results

It is not normal for test results to give a base-by-base list of results. Instead, results are normally compared to the Cambridge Reference Sequence (CRS), which is the mitochondria of a European who was the first person to have their mtDNA published in 1981 (and revised in 1999). Differences between the CRS and testers are usually very few, thus it is more convenient than listing one's raw results for each base pair.
Examples
Note that in HVR1, instead of reporting the base pair exactly, for example 16,111, the 16 is often removed to give in this example 111. The letters refer to one of the four bases (A, T, G, C) that make up DNA.

Region HVR1 HVR2
Differences from CRS 111T,223T,259T,290T,319A,362C 073G,146C,153G

Y chromosome (Y-DNA) testing

The Y-Chromosome is one of the 23rd pair of human chromosomes. Only males have a Y-chromosome, because women have two X chromosomes in their 23rd pair. A man's patrilineal ancestry, or male-line ancestry, can be traced using the DNA on his Y chromosome (Y-DNA), because the Y-chromosome is transmitted father to son nearly unchanged. A man's test results are compared to another man's results to determine the time frame in which the two individuals shared a most recent common ancestor, or MRCA, in their direct patrilineal lines. If their test results are very close, they are related within a genealogically useful time frame. A surname project is where many individuals whose Y-chromosomes match collaborate to find their common ancestry.

Women who wish to determine their direct paternal DNA ancestry can ask their father, brother, paternal uncle, paternal grandfather, or a paternal uncle's son (their cousin) to take a test for them.
There are two types of DNA testing: STRs and SNPs.

STR markers

Most common is STRs (short tandem repeat). A certain section of DNA is examined for a pattern that repeats (e.g. ATCG). The number of times it repeats is the value of the marker. Typical tests test between 12 and 111 STR markers. STRs mutate fairly frequently. The results of two individuals are then compared to see if there is a match. DNA companies will usually provide an estimate of how closely related two people are, in terms of generations or years, based on the difference between their results.

SNP markers and Haplogroups

Strand 1 differs from strand 2 at a single base pair location (a C → T polymorphism).
 
A person's haplogroup can often be inferred from their STR results, but can be proven only with a Y-chromosome SNP test (Y-SNP test).

A single-nucleotide polymorphism (SNP) is a change to a single nucleotide in a DNA sequence. Typical Y-DNA SNP tests test about 20,000 to 35,000 SNPs. Getting a SNP test allows a much higher resolution than STRs. It can be used to provide additional information about the relationship between two individuals and to confirm haplogroups. 

The most common Y-DNA-haplogroup in different regions in Europe
 
All human men descend in the paternal line from a single man dubbed Y-chromosomal Adam, who lived probably between 200,000 and 400,000 years ago. A 'family tree' can be drawn showing how men today descend from him. Different branches of this tree are different haplogroups. Most haplogroups can be further subdivided multiple times into sub-clades. Some known sub-clades were founded in the last 1000 years, meaning their timeframe approaches the genealogical era (c.1500 onwards).

New sub-clades of haplogroups may be discovered when an individual tests, especially if they are non-European. Most significant of these new discoveries was in 2013 when the haplogroup A00 was discovered, which required theories about Y-chromosomal Adam to be significantly revised. The haplogroup was discovered when an African-American man tested STRs at FamilyTreeDNA and his results were found to be unusual. SNP testing confirmed that he does not descend patrilineally from the "old" Y-chromosomal Adam and so a much older man became Y-Chromosomal Adam.

Using DNA test results

Ethnicity estimates

Many companies offer a percentage breakdown by ethnicity or region. Generally the world is specified into about 20–25 regions, and the approximate percentage of DNA inherited from each is stated. This is usually done by comparing the frequency of each Autosomal DNA marker tested to many population groups. The reliability of this type of test is dependent on comparative population size, the number of markers tested, the ancestry informative value of the SNPs tested, and the degree of admixture in the person tested. Earlier ethnicity estimates were often wildly inaccurate, but as companies receive more samples over time, ethnicity estimates have become more accurate. Testing companies such as Ancestry.com will often regularly update their ethnicity estimates, which has caused some controversy from customers as their results update. Usually the results at the continental level are accurate, but more specific assertions of the test may turn out to be incorrect.

Audience

The interest in genealogical DNA tests has been linked to both an increase in curiosity about traditional genealogy and to more general personal origins. Those who test for traditional genealogy often utilize a combination of autosomal, mitochondrial, and Y-Chromosome tests. Those with an interest in personal ethnic origins are more likely to use an autosomal test. However, answering specific questions about the ethnic origins of a particular lineage may be best suited to an mtDNA test or a Y-DNA test.

Maternal origin tests

For recent genealogy, exact matching on the mtDNA full sequence is used to confirm a common ancestor on the direct maternal line between two suspected relatives. Because mtDNA mutations are very rare, a nearly perfect match is not usually considered relevant to the most recent 1 to 16 generations. In cultures lacking matrilineal surnames to pass down, neither relative above is likely to have as many generations of ancestors in their matrilineal information table as in the above patrilineal or Y-DNA case: for further information on this difficulty in traditional genealogy, due to lack of matrilineal surnames (or matrinames), see Matriname. However, the foundation of testing is still two suspected descendants of one person. This hypothesize and test DNA pattern is the same one used for autosomal DNA and Y-DNA.

Tests for ethnicity and membership of other groups

European genetic structure (based on Autosomal SNPs) by PCA
 
As discussed above, autosomal tests usually report the ethnic proportions of the individual. These attempt to measure an individual's mixed geographic heritage by identifying particular markers, called ancestry informative markers or AIM, that are associated with populations of specific geographical areas. Geneticist Adam Rutherford has written that these tests "don’t necessarily show your geographical origins in the past. They show with whom you have common ancestry today."

The haplogroups determined by Y-DNA and mtDNA tests are often unevenly geographically distributed. Many direct-to-consumer DNA tests described this association to infer the test-taker's ancestral homeland. Most tests describe haplogroups according to their most frequently associated continent (e.g., a "European haplogroup"). When Leslie Emery and collaborators performed a trial of mtDNA haplogroups as a predictor of continental origin on individuals in the Human Genetic Diversity Panel (HGDP) and 1000 Genomes (1KGP) datasets, they found that only 14 of 23 haplogroups had a success rate above 50% among the HGDP samples, as did "about half" of the haplogroups in the 1KGP. The authors concluded that, for most people, "mtDNA-haplogroup membership provides limited information about either continental ancestry or continental region of origin."

African ancestry

Y-DNA and mtDNA testing may be able to determine with which peoples in present-day Africa a person shares a direct line of part of his or her ancestry, but patterns of historic migration and historical events cloud the tracing of ancestral groups. Due to joint long histories in the US, approximately 30% of African American males have a European Y-Chromosome haplogroup Approximately 58% of African Americans have at least the equivalent of one great-grandparent (13%) of European ancestry. Only about 5% have the equivalent of one great-grandparent of Native American ancestry. By the early 19th century, substantial families of Free Persons of Color had been established in the Chesapeake Bay area who were descended from free people during the colonial period; most of those have been documented as descended from white men and African women (servant, slave or free). Over time various groups married more within mixed-race, black or white communities.

According to authorities like Salas, nearly three-quarters of the ancestors of African Americans taken in slavery came from regions of West Africa. The African-American movement to discover and identify with ancestral tribes has burgeoned since DNA testing became available. African Americans usually cannot easily trace their ancestry during the years of slavery through surname research, census and property records, and other traditional means. Genealogical DNA testing may provide a tie to regional African heritage.

United States – Melungeon testing

Melungeons are one of numerous multiracial groups in the United States with origins wrapped in myth. The historical research of Paul Heinegg has documented that many of the Melungeon groups in the Upper South were descended from mixed-race people who were free in colonial Virginia and the result of unions between the Europeans and Africans. They moved to the frontiers of Virginia, North Carolina, Kentucky and Tennessee to gain some freedom from the racial barriers of the plantation areas. Several efforts, including a number of ongoing studies, have examined the genetic makeup of families historically identified as Melungeon. Most results point primarily to a mixture of European and African, which is supported by historical documentation. Some may have Native American heritage as well. Though some companies provide additional Melungeon research materials with Y-DNA and mtDNA tests, any test will allow comparisons with the results of current and past Melungeon DNA studies

Native American ancestry

The pre-columbian indigenous people of the United States are called "Native Americans" in American English. Autosomal testing, Y-DNA, and mtDNA testing can be conducted to determine the ancestry of Native Americans. A mitochondrial Haplogroup determination test based on mutations in Hypervariable Region 1 and 2 may establish whether a person's direct female line belongs to one of the canonical Native American Haplogroups, A, B, C, D or X. The vast majority of Native American individuals belong to one of the five identified mtDNA Haplogroups. Thus, being in one of those groups provides evidence of potential Native American descent. However, DNA ethnicity results cannot be used as a substitute for legal documentation. Native American tribes have their own requirements for membership, often based on at least one of a person's ancestors having been included on tribal-specific Native American censuses (or final rolls) prepared during treaty-making, relocation to reservations or apportionment of land in the late 19th century and early 20th century. One example is the Dawes Rolls.

Cohanim ancestry

The Cohanim (or Kohanim) is a patrilineal priestly line of descent in Judaism. According to the Bible, the ancestor of the Cohanim is Aaron, brother of Moses. Many believe that descent from Aaron is verifiable with a Y-DNA test: the first published study in genealogical Y-Chromosome DNA testing found that a significant percentage of Cohens had distinctively similar DNA, rather more so than general Jewish or Middle Eastern populations. These Cohens tended to belong to Haplogroup J, with Y-STR values clustered unusually closely around a haplotype known as the Cohen Modal Haplotype (CMH). This could be consistent with a shared common ancestor, or with the hereditary priesthood having originally been founded from members of a single closely related clan.

Nevertheless, the original studies tested only six Y-STR markers, which is considered a low-resolution test. In response to the low resolution of the original 6-marker CMH, the testing company FTDNA released a 12-marker CMH signature that was more specific to the large closely related group of Cohens in Haplogroup J1. 

A further academic study published in 2009 examined more STR markers and identified a more sharply defined SNP haplogroup, J1e* (now J1c3, also called J-P58*) for the J1 lineage. The research found "that 46.1% of Kohanim carry Y chromosomes belonging to a single paternal lineage (J-P58*) that likely originated in the Near East well before the dispersal of Jewish groups in the Diaspora. Support for a Near Eastern origin of this lineage comes from its high frequency in our sample of Bedouins, Yemenis (67%), and Jordanians (55%) and its precipitous drop in frequency as one moves away from Saudi Arabia and the Near East (Fig. 4). Moreover, there is a striking contrast between the relatively high frequency of J-58* in Jewish populations (»20%) and Kohanim (»46%) and its vanishingly low frequency in our sample of non-Jewish populations that hosted Jewish diaspora communities outside of the Near East."

Recent phylogenetic research for haplogroup J-M267 placed the "Y-chromosomal Aaron" in a subhaplogroup of J-L862, L147.1 (age estimate 5631-6778yBP yBP): YSC235>PF4847/CTS11741>YSC234>ZS241>ZS227>Z18271 (age estimate 2731yBP).

Benefits

Genealogical DNA tests have become popular due to the ease of testing at home and their usefulness in supplementing genealogical research. Genealogical DNA tests allow for an individual to determine with high accuracy whether he or she is related to another person within a certain time frame, or with certainty that he or she is not related. DNA tests are perceived as more scientific, conclusive and expeditious than searching the civil records. However, they are limited by restrictions on lines that may be studied. The civil records are always only as accurate as the individuals having provided or written the information.

Y-DNA testing results are normally stated as probabilities: For example, with the same surname a perfect 37/37 marker test match gives a 95% likelihood of the most recent common ancestor (MRCA) being within 8 generations, while a 111 of 111 marker match gives the same 95% likelihood of the MRCA being within only 5 generations back.

As presented above in mtDNA testing, if a perfect match is found, the mtDNA test results can be helpful. In some cases, research according to traditional genealogy methods encounters difficulties due to the lack of regularly recorded matrilineal surname information in many cultures (see Matrilineal surname).

Autosomal DNA combined with genealogical research has been used by adoptees to find their biological parents, has been used to find the name and family of unidentified bodies and by law enforcement agencies to apprehend criminals (for example, the Contra Costa County District Attorney's office used the "open-source" genetic genealogy site GEDmatch to find relatives of the suspect in the Golden State Killer case.). The Atlantic magazine commented in 2018 that "Now, the floodgates are open. ..a small, volunteer-run website, GEDmatch.com, has become ... the de facto DNA and genealogy database for all of law enforcement." Family Tree DNA announced in February 2019 it was allowing the FBI to access its DNA data for cases of murder and rape. However in May 2019 GEDmatch initiated stricter rules for accessing their autosomal DNA database and Family Tree DNA shut down their Y-DNA database ysearch.org, making it more difficult for law enforcement agencies to solve cases.

Drawbacks

Common concerns about genealogical DNA testing are cost and privacy issues. Some testing companies retain samples and results for their own use without a privacy agreement with subjects.

Autosomal DNA tests can identify relationships but they can be misinterpreted. For example, transplants of stem cell or bone marrow will produce matches with the donor. In addition, identical twins (who have identical DNA) can give unexpected results.

Testing of the Y-DNA lineage from father to son may reveal complications, due to unusual mutations, secret adoptions, and non-paternity events (i.e., that the perceived father in a generation is not the father indicated by written birth records). According to the Ancestry and Ancestry Testing Task Force of the American Society of Human Genetics, autosomal tests cannot detect "large portions" of DNA from distant ancestors because it has not been inherited.

With the increasing popularity of the use of DNA tests for ethnicity tests, uncertainties and errors in ethnicity estimates are a drawback for Genetic genealogy. While ethnicity estimates at the continental level should be accurate (with the possible exception of East Asia and the Americas), sub-continental estimates, especially in Europe, are often inaccurate. Customers may be misinformed about the uncertainties and errors of the estimates.

Some have recommended government or other regulation of ancestry testing to ensure its performance to an agreed standard.

A number of law enforcement agencies took legal action to compel genetic genealogy companies to release genetic information that could match cold case crime victims or perpetrators. A number of companies fought the requests.

Medical information

Though genealogical DNA tests are not designed mainly for medical purposes, autosomal DNA tests can be used to analyze the probability of hundreds of heritable medical conditions, albeit the result is complex to understand and may confuse a non-expert. 23andMe provides medical and trait information from their genealogical DNA test and for a fee the Promethease web site analyses genealogical DNA test data from Family Tree DNA, 23andMe, or AncestryDNA for medical information. Promethease, and its research paper crawling database SNPedia, has received criticism for technical complexity and a poorly defined "magnitude" scale that causes misconceptions, confusion and panic among its users.

The testing of full MtDNA and YDNA sequences is still somewhat controversial as it may reveal even more medical information. For example, a correlation exists between a lack of Y-DNA marker DYS464 and infertility, and between mtDNA haplogroup H and protection from sepsis. Certain haplogroups have been linked to longevity in some population groups. The field of linkage disequilibrium, unequal association of genetic disorders with a certain mitochondrial lineage, is in its infancy, but those mitochondrial mutations that have been linked are searchable in the genome database Mitomap. Family Tree DNA's MtFull Sequence test analyses the full MtDNA genome and the National Human Genome Research Institute operates the Genetic And Rare Disease Information Center that can assist consumers in identifying an appropriate screening test and help locate a nearby medical center that offers such a test.

DNA in genealogy software

Some genealogy software programs — such as Family Tree Maker, Legacy Family Tree (Deluxe Edition) and the Swedish program Genney — allow recording DNA marker test results. This allows for tracking of both Y-chromosome and mtDNA tests, and recording results for relatives.

Lie group

From Wikipedia, the free encyclopedia https://en.wikipedia.org/wiki/Lie_group In mathematics , a Lie gro...