Information warfare (IW) is the battlespace use and management of information and communication technology (ICT) in pursuit of a competitive advantage over an opponent. It is different from cyberwarfare
that attacks computers, software, and command control systems.
Information warfare is the manipulation of information trusted by a
target without the target's awareness so that the target will make
decisions against their interest but in the interest of the one
conducting information warfare. As a result, it is not clear when information warfare begins, ends, and how strong or destructive it is.
Information warfare may involve the collection of tactical information, assurance(s) that one's information is valid, spreading of propaganda or disinformation to demoralize or manipulate
the enemy and the public, undermining the quality of the opposing
force's information, and denial of information-collection opportunities
to opposing forces. Information warfare is closely linked to psychological warfare.
Information warfare has been described as "the use of information to achieve our national objectives."[6] According to NATO, "Information war is an operation conducted in order to gain an information advantage over the opponent."
The organized use of social media and other online content-generation platforms can be used to influence public perceptions.
The United States Air Force
has had Information Warfare Squadrons since the 1980s. In fact, the
official mission of the U.S. Air Force is now "To fly, fight and win...
in air, space and cyberspace", with the latter referring to its information warfare role.
As the U.S. Air Force often risks aircraft and aircrews to attack
strategic enemy communications targets, remotely disabling such targets
using software and other means can provide a safer alternative. In
addition, disabling such networks electronically (instead of
explosively) also allows them to be quickly re-enabled after the enemy
territory is occupied. Similarly, counter-information warfare units are
employed to deny such capability to the enemy. The first application of
these techniques was used against Iraqi communications networks in the Gulf War.
Also during the Gulf War, Dutch hackers allegedly stole information about U.S. troop movements from U.S. Defense Department computers and tried to sell it to the Iraqis, who thought it was a hoax and turned it down. In January 1999, U.S. Air Intelligence computers were hit by a coordinated attack (Moonlight Maze),
part of which came from a Russian mainframe. This could not be
confirmed as a Russian cyber attack due to non-attribution – the
principle that online identity may not serve as proof of real-world
identity.
New battlefield
Within the realm of cyberspace, there are two primary weapons: network-centric warfare and C4ISR,
which denotes integrated Command, Control, Communications, Computers,
Intelligence, Surveillance and Reconnaissance. Furthermore, cyberspace
attacks initiated by one nation against another nation have an
underlying goal of gaining information superiority
over the attacked party, which includes disrupting or denying the
victimized party's ability to gather and distribute information. A
real-world occurrence that illustrated the dangerous potential of
cyberattacks transpired in 2007, when a strike from Israeli forces demolished an alleged nuclear reactor in Syria
that was being constructed via a collaborative effort between Syria and
North Korea. Accompanied by the strike was a cyberattack on Syria's air
defenses, which left them blind to the attack on the nuclear reactor
and, ultimately allowed for the attack to occur (New York Times 2014).
An example of a more basic attack on a nation within cyberspace is a distributed denial of service
(DDOS) attack, which is utilized to hinder networks or websites until
they lose their primary functionality. As implied, cyberattacks do not
just affect the military party being attacked, but rather the whole
population of the victimized nation. Since more aspects of daily life
are being integrated into networks in cyberspace, civilian populations
can potentially be negatively affected during wartime. For example, if a
nation chose to attack another nation's power grid servers in a specific area to disrupt communications, civilians and businesses in that area would also have to deal with power outages, which could potentially lead to economic disruptions as well.
Moreover, physical ICTs have also been implemented into the
latest revolution in military affairs by deploying new, more autonomous
robots (i.e. – unmanned drones)
into the battlefield to carry out duties such as patrolling borders and
attacking ground targets. Humans from remote locations pilot many of
the unmanned drones, however, some of the more advanced robots, such as
the Northrop Grumman X-47B,
are capable of autonomous decisions. Despite piloting drones from
remote locations, a proportion of drone pilots still suffer from stress
factors of more traditional warfare. According to NPR, a study performed
by the Pentagon in 2011 found that 29% of drone pilots are "burned out"
and undergo high levels of stress. Furthermore, approximately 17% of
the drone pilots surveyed as the study were labeled "clinically
distressed" with some of those pilots also showing signs of post-traumatic stress disorder.
Modern ICTs have also brought advancements to communications
management among military forces. Communication is a vital aspect of war
for any involved party and, through the implementation of new ICTs such
as data-enabled devices, military forces are now able to disseminate information faster than ever before. For example, some militaries are now employing the use of iPhones to upload data and information gathered by drones in the same area.
In 2022, the Armed Forces of Ukraine
have taken advantage of deficiencies in Russian communications by
allowing them to piggyback on Ukrainian networks, connect, and
communicate. Ukrainian forces then eavesdrop, and cut off Russian
communications at a crucial part of the conversation.
To build support before it invaded Ukraine, Russia
perpetuated a narrative that claimed the Ukrainian government was
committing violence against its own Russian speaking population. By
publishing large amounts of disinformation on the internet, the
alternate narrative was picked up in search results, such as Google News.
Research
suggests that Russia and the West are also engaged in an information
war. For instance, Russia believes that the West is undermining its
leader through the encouragement of overthrowing authoritarian regimes
and liberal values. In response, Russia promotes the anti-liberal
sentiments, including racism, antisemitism, homophobia, and misogyny. Russia has sought to promote the idea that the American democratic state is failing.
Russia, China and pro-Palestinian protests
The Telegraph reported in 2024 that China and Russia were promoting pro-Palestinianinfluencers in order to manipulate British public opinion in favor of Russian and Chinese interests.
NBC reported that Russia was using different tools to cause division
within the US, by delegitimizing US police operations against Pro
Palestinian protests and by pivoting public conversation from the
Russian invasion in Ukraine to the Israeli-Palestinian conflict. Russian media activity increased by 400% in the weeks after Hamas’ Oct. 7 attack on Israel.
United States COVID-19 disinformation campaign
According to a report by Reuters, the United States ran a propaganda campaign to spread disinformation about the Sinovac Chinese COVID-19
vaccine, including using fake social media accounts to spread the
disinformation that the Sinovac vaccine contained pork-derived
ingredients and was therefore haram under Islamic law. The campaign was described as "payback" for COVID-19 disinformation by China directed against the U.S. The campaign primarily targeted people in the Philippines and used a social media hashtag for "China is the virus" in Tagalog. The campaign ran from 2020 to mid-2021. The primary contractor for the U.S. military on the project was General Dynamics IT, which received $493 million for its role.
Legal and ethical concerns
While
information warfare has yielded many advances in the types of attack
that a government can make, it has also raised concerns about the moral
and legal ambiguities surrounding this particularly new form of war.
Traditionally, wars have been analyzed by moral scholars according to just war theory.
However, with Information Warfare, Just War Theory fails because the
theory is based on the traditional conception of war. Information
Warfare has three main issues surrounding it compared to traditional
warfare:
The risk for the party or nation initiating the cyberattack is
substantially lower than the risk for a party or nation initiating a
traditional attack. This makes it easier for governments, as well as
potential terrorist or criminal organizations, to make these attacks more frequently than they could with traditional war.
Information communication technologies (ICT) are so immersed in the
modern world that a very wide range of technologies are at risk of a
cyberattack. Specifically, civilian technologies can be targeted for
cyberattacks and attacks can even potentially be launched through
civilian computers or websites. As such, it is harder to enforce
control of civilian infrastructures than a physical space. Attempting to
do so would also raise many ethical concerns about the right to
privacy, making defending against such attacks even tougher.
The mass-integration of ICT into our system of war makes it much
harder to assess accountability for situations that may arise when using
robotic and/or cyber attacks. For robotic weapons and automated
systems, it's becoming increasingly hard to determine who is responsible
for any particular event that happens. This issue is exacerbated in
the case of cyberattacks, as sometimes it is virtually impossible to
trace who initiated the attack in the first place.
Recently, legal concerns have arisen centered on these issues, specifically the issue of the right to privacy in the United States of America. Lt. General Keith B. Alexander, who served as the head of Cyber Command under President Barack Obama,
noted that there was a "mismatch between our technical capabilities to
conduct operations and the governing laws and policies" when writing to
the Senate Armed Services Committee.
A key point of concern was the targeting of civilian institutions for
cyberattacks, to which the general promised to try to maintain a mindset
similar to that of traditional war, in which they will seek to limit
the impact on civilians.
The argument from poor design, also known as the dysteleological argument, is an argument against the assumption of the existence of a creatorGod, based on the reasoning that any omnipotent and omnibenevolent deity or deities would not create organisms with the perceived suboptimal designs that occur in nature.
The argument is structured as a basic modus ponens:
if "creation" contains many defects, then design appears an implausible
theory for the origin of earthly existence. Proponents most commonly
use the argument in a weaker way, however: not with the aim of
disproving the existence of God, but rather as a reductio ad absurdum of the well-known argument from design (which suggests that living things appear too well-designed to have originated by chance, and so an intelligent God or gods must have deliberately created them).
Although the phrase "argument from poor design" has seen little
use, this type of argument has been advanced many times using words and
phrases such as "poor design", "suboptimal design", "unintelligent
design" or "dysteleology/dysteleological". The nineteenth-century biologist Ernst Haeckel applied the term "dysteleology" to the implications of organs so rudimentary as to be useless to the life of an organism. In his 1868 book Natürliche Schöpfungsgeschichte (The History of Creation),
Haeckel devoted most of a chapter to the argument, ending with the
proposition (perhaps with tongue slightly in cheek) of "a theory of the unsuitability of parts in organisms, as a counter-hypothesis to the old popular doctrine of the suitability of parts". In 2005, Donald Wise of the University of Massachusetts Amherst popularised the term "incompetent design" (a play on "intelligent design"), to describe aspects of nature seen as flawed in design.
Traditional Christian theological responses generally posit that
God constructed a perfect universe but that humanity's misuse of its free will to rebel against God has resulted in the corruption of divine good design.
Overview
Natural selection is expected to push fitness to a peak, but that peak often is not the highest.
Living things are too well-designed to have originated by chance.
Therefore, life must have been created by an intelligent creator.
This creator is God.
"Poor design" is consistent with the predictions of the scientific theory of evolution by means of natural selection.
This predicts that features that were evolved for certain uses are then
reused or co-opted for different uses, or abandoned altogether; and
that suboptimal state is due to the inability of the hereditary mechanism to eliminate the particular vestiges of the evolutionary process.
In fitness landscape
terms, natural selection will always push "up the hill", but a species
cannot normally get from a lower peak to a higher peak without first
going through a valley.
The argument from poor design is one of the arguments that was used by Charles Darwin; modern proponents have included Stephen Jay Gould, Richard Dawkins, and Nathan H. Lents.
They argue that such features can be explained as a consequence of the
gradual, cumulative nature of the evolutionary process. Theistic evolutionists generally reject the argument from design, but do still maintain belief in the existence of God.
American scientist Nathan H. Lents published his book on poor design in the human body and genome in 2018 titled Human Errors. The book ignited a firestorm of criticism from the creationist community but was well received by the scientific community and received unanimously favorable reviews in the dozens of non-creationist media outlets that covered it.
Several defects in human anatomy can result in death, especially without modern medical care:
In the human female, a fertilized egg can implant into the fallopian tube, cervix or ovary rather than the uterus causing an ectopic pregnancy.
The existence of a cavity between the ovary and the fallopian tube
could indicate a flawed design in the female reproductive system. Prior
to modern surgery, ectopic pregnancy invariably caused the deaths of
both mother and baby. Even in modern times, in almost all cases the
pregnancy must be aborted to save the life of the mother.
In the human female, the birth canal passes through the pelvis.
The prenatal skull will deform to a surprising extent. However, if the
baby's head is significantly larger than the pelvic opening, the baby
cannot be born naturally. Prior to the development of modern surgery (caesarean section), such a complication would lead to the death of the mother, the baby, or both. Other birthing complications such as breech birth are worsened by this position of the birth canal.
In the human male, testes develop initially within the abdomen. Later during gestation, they migrate through the abdominal wall into the scrotum. This causes two weak points in the abdominal wall where hernias can later form. Prior to modern surgical techniques, complications from hernias, such as intestinal blockage and gangrene, usually resulted in death.
The existence of the pharynx, a passage used for both ingestion and respiration, with the consequent drastic increase in the risk of choking.
The breathing reflex is stimulated not directly by the absence of oxygen but indirectly by the presence of carbon dioxide. This means that high concentrations of inert gases, such as nitrogen and helium,
can cause suffocation without any biological warning. Furthermore, at
high altitudes, oxygen deprivation can occur in unadapted individuals
who do not consciously increase their breathing rate.
The human appendix is a vestigial organ thought to serve no purpose. Appendicitis,
an infection of this organ, is a certain death without medical
intervention. "During the past few years, however, several studies have
suggested its immunological importance for the development and
preservation of the intestinal immune system."
Tinnitus, a phantom auditory sensation, is a maladaptation resulting from hearing loss most often caused by exposure to loud noise. Tinnitus serves no practical purpose, reduces quality of life, may cause depression, and when severe can lead to suicide.
Other flaws
Barely used nerves and muscles, such as the plantaris muscle of the foot,
that are missing in part of the human population and are routinely
harvested as spare parts if needed during operations. Another example is
the muscles that move the ears, which some people can learn to control
to a degree, but serve no purpose in any case.
The common malformation of the human spinal column, leading to scoliosis, sciatica and congenital misalignment of the vertebrae. The spinal cord
cannot ever properly heal if it is damaged, because neurons have become
so specialized that they are no longer able to regrow once they reach
their mature state. The spinal cord, if broken, will never repair itself
and will result in permanent paralysis.
The route of the recurrent laryngeal nerve is such that it travels from the brain to the larynx by looping around the aortic arch. This same configuration holds true for many animals; in the case of the giraffe, this results in about twenty feet of extra nerve.
Almost all animals and plants synthesize their own vitamin C, but humans cannot because the gene for this enzyme is defective (Pseudogene ΨGULO). Lack of vitamin C results in scurvy and eventually death. The gene is also non-functional in other primates and in guinea pigs, but is functional in most other animals.
The male urethra passes directly through the prostate, which can produce urinary difficulties if the prostate becomes swollen.
Crowded teeth and poor sinus drainage, as human faces are significantly flatter than those of other primates although humans share the same tooth set. This results in a number of problems, most notably with wisdom teeth, which can damage neighboring teeth or cause serious infections of the mouth.
The structure of human eyes (as well as those of all vertebrates). The retina is 'inside out'. The nerves and blood vessels lie on the surface of the retina instead of behind it as is the case in many invertebrate species. This arrangement forces a number of complex adaptations and gives mammals a blind spot. Having the optic nerve connected to the side of the retina that does not receive the light, as is the case in cephalopods, would avoid these problems. Lents and colleagues have proposed that the tapetum lucidum, the reflective surface behind vertebrate retinas, has evolved to overcome the limitations of the inverted retina, as cephalopods have never evolved this structure. However, an 'inverted' retina actually improves image quality through müller cells by reducing distortion. The effects of the blind spots resulting from the inverted retina are cancelled by binocular vision, as the blind spots in both eyes are oppositely angled. Additionally, as cephalopod eyes
lack cone cells and might be able to judge color by bringing specific
wavelengths to a focus on the retina, an inverted retina might interfere
with this mechanism.
The existence of unnecessary wings in flightless birds, e.g. ostriches.
The enzyme RuBisCO has been described as a "notoriously inefficient" enzyme, as it is inhibited
by oxygen, has a very slow turnover and is not saturated at current
levels of carbon dioxide in the atmosphere. The enzyme is inhibited as
it is unable to distinguish between carbon dioxide and molecular oxygen,
with oxygen acting as a competitive enzyme inhibitor. However, RuBisCO remains the key enzyme in carbon fixation,
and plants overcome its poor activity by having massive amounts of it
inside their cells, making it the most abundant protein on Earth.
Sturdy but heavy bones, suited for non-flight, occurring in animals
like bats. Or, on the converse: unstable, light, hollow bones, suited
for flight, occurring in birds like penguins and ostriches, which cannot
fly.
Various vestigial body parts, like the femur and pelvis in whales (evolution indicates the ancestors of whales lived on land).
Many species have strong instincts to behave in response to a
certain stimulus. Natural selection can leave animals behaving in
detrimental ways when they encounter a supernormal stimulus - like a moth flying into a flame.
Plants are green and not black, as chlorophyll absorbs green light poorly, even though black plants would absorb more light energy.
Whales and dolphins breathe air, but live in the water, meaning they must swim to the surface frequently to breathe.
Intelligent design proponent William Dembski questions the first premise of the argument, claiming that "intelligent design" does not need to be optimal.
While the appendix
has been previously credited with very little function, research has
shown that it serves an important role in the fetus and young adults.
Endocrine cells appear in the appendix of the human fetus at around the
11th week of development, which produce various biogenic amines and
peptide hormones, compounds that assist with various biological control
(homeostatic) mechanisms. In young adults, the appendix has some immune
functions.
Responses to counterarguments
In response to the claim that uses have been found for "junk" DNA, proponents note that the fact that some non-coding DNA has a purpose does not establish that all non-coding DNA has a purpose, and that the human genome does include pseudogenes
that are nonfunctional "junk", with others noting that some sections of
DNA can be randomized, cut, or added to with no apparent effect on the
organism in question. The original study that suggested that the Makorin1-p1 served some purpose has been disputed.
However, the original study is still frequently cited in newer studies
and articles on pseudogenes previously thought to be nonfunctional.
As an argument regarding God
The argument from poor design is sometimes interpreted, by the argumenter or the listener, as an argument against the existence of God, or against characteristics commonly attributed to a creator deity, such as omnipotence, omniscience,
or personality. In a weaker form, it is used as an argument for the
incompetence of God. The existence of "poor design" (as well as the
perceived prodigious "wastefulness" of the evolutionary process) would
seem to imply a "poor" designer, or a "blind" designer, or no designer
at all. In Gould's words, "If God had designed a beautiful machine to
reflect his wisdom and power, surely he would not have used a collection
of parts generally fashioned for other purposes. Orchids are not made
by an ideal engineer; they are jury-rigged...."
The apparently suboptimal design of organisms has also been used by proponents of theistic evolution to argue in favour of a creator deity who uses natural selection as a mechanism of his creation. Arguers from poor design regard counter-arguments as a false dilemma,
imposing that either a creator deity designed life on earth well or
flaws in design indicate the life is not designed. This allows
proponents of intelligent design to cherry pick which aspects of life constitute design, leading to the unfalsifiability
of the theory. Christian proponents of both intelligent design and
creationism may claim that good design indicates the creative
intelligence of their God, while poor design indicates corruption of the
world as a result of free will that caused the fall of man (for example, in Genesis 3:16 Yahweh says to Eve "I will increase your trouble in pregnancy").
Adaptationism is a scientific perspective on evolution that
focuses on accounting for the products of evolution as collections of
adaptive traits, each a product of natural selection with some adaptive
rationale.
A formal alternative would be to look at the products of
evolution as the result of neutral evolution, in terms of structural
constraints, or in terms of a mixture of factors including (but not
limited to) natural selection.
The most obvious justification for an adaptationist perspective
is the belief that traits are, in fact, always adaptations built by
natural selection for their functional role. This position is called
"empirical adaptationism" by Godfrey-Smith.
However, Godfrey-Smith also identifies "methodological" and
"explanatory" flavors of adaptationism, and argues that all three are
found in the evolutionary literature.
Although adaptationism has always existed— the view that the
features of organisms are wonderfully adapted predates evolutionary
thinking— and was sometimes criticized for its "Panglossian" excesses
(e.g., by Bateson or Haldane), concerns about the role of adaptationism
in scientific research did not become a major issue of debate until
evolutionary biologists Stephen Jay Gould and Richard Lewontin penned a famous critique, "The Spandrels of San Marco and the Panglossian Paradigm". According to Gould and Lewontin, evolutionary biologists had a habit of
proposing adaptive explanations for any trait by default without
considering non-adaptive alternatives, and often by conflating products
of adaptation with the process of natural selection. They identified neutral evolution and developmental constraints as potentially important non-adaptive factors and called for alternative research agendas.
This critique provoked defenses by Mayr, Reeve and Sherman
and others, who argued that the adaptationist research program was
unquestionably highly successful, and that the causal and methodological
basis for considering alternatives was weak. The "Spandrels paper" (as
it came to be known) also added fuel to the emergence of an alternative
"evo-devo" agenda focused on developmental "constraints"
Today, molecular evolutionists often cite neutral evolution as the
null hypothesis in evolutionary studies, i.e., offering a direct
contrast to the adaptationist approach. Constructive neutral evolution
has been suggested as a means by which complex systems emerge through
neutral transitions, and has been invoked to help understand the origins
of a wide variety of features from the spliceosome of eukaryotes to the interdependency and simplification widespread in microbial communities.
Today, adaptationism is associated with the "reverse engineering" approach. Richard Dawkins noted in The Blind Watchmaker that evolution, an impersonal process, produces organisms that give the appearance of having been designed for a purpose.
This observation justifies looking for the function of traits observed
in biological organisms. This reverse engineering is used in disciplines
such as psychology and economics
to explain the features of human cognition. Reverse engineering can, in
particular, help explain cognitive biases as adaptive solutions that
assist individuals in decision-making when considering constraints such
as the cost of processing information. This approach is valuable in
understanding how seemingly irrational behaviors may, in fact, be
optimal given the environmental and informational limitations under
which human cognition operates.
Overview
Criteria to identify a trait as an adaptation
Adaptationism
is an approach to studying the evolution of form and function. It
attempts to frame the existence and persistence of traits, assuming that
each of them arose independently and improved the reproductive success
of the organism's ancestors.
A trait is an adaptation if it fulfils the following criteria:
The trait is a variation of an earlier form.
The trait is heritable through the transmission of genes.
The trait enhances reproductive success.
Constraints on the power of evolution
Genetic constraints
Genetic reality provides constraints on the power of random mutation followed by natural selection.
With pleiotropy,
some genes control multiple traits, so that adaptation of one trait is
impeded by effects on other traits that are not necessarily adaptive.
Selection that influences epistasis
is a case where the regulation or expression of one gene, depends on
one or several others. This is true for a good number of genes though to
differing extents. The reason why this leads to muddied responses is
that selection for a trait that is epistatically based can mean that an allele
for a gene that is epistatic when selected would happen to affect
others. This leads to the coregulation of others for a reason other than
there is an adaptive quality to each of those traits. Like with
pleiotropy, traits could reach fixation in a population as a by-product
of selection for another.
In the context of development the difference between pleiotropy
and epistasis is not so clear but at the genetic level the distinction
is more clear. With these traits as being by-products of others it can
ultimately be said that these traits evolved but not that they
necessarily represent adaptations.
Polygenic
traits are controlled by a number of separate genes. Many traits are
polygenic, for example human height. To drastically change a polygenic
trait is likely to require multiple changes.
Anatomical constraints
Anatomical constraints are features of organism's anatomy
that are prevented from change by being constrained in some way. When
organisms diverge from a common ancestor and inherit certain
characteristics which become modified by natural selection of mutant
phenotypes, it is as if some traits are locked in place and are unable
to change in certain ways. Some textbook anatomical constraints often include examples of structures that connect parts of the body together though a physical link.
These links are hard if not impossible to break because evolution
usually requires that anatomy be formed by small consecutive
modifications in populations through generations. In his book, Why We Get Sick, Randolph Nesse uses the "blind spot" in the vertebrate eye (caused by the nerve fibers running through the retina) as an example of this. He argues that natural selection
has come up with an elaborate work-around of the eyes wobbling
back-and-forth to correct for this, but vertebrates have not found the
solution embodied in cephalopod eyes, where the optic nerve does not interrupt the view. See also: Evolution of the eye.
Another example is the cranial nerves in tetrapods. In early vertebrate evolution, sharks, skates, and rays (collectively Chondrichthyes),
the cranial nerves run from the part of the brain that interprets
sensory information, and radiate out towards the organs that produce
those sensations. In tetrapods, however, and mammals in particular, the nerves take an elaborate winding path through the cranium around structures that evolved after the common ancestor with sharks.
Adaptationism is sometimes characterized by critics as an unsubstantiated assumption that all or most traits are optimal adaptations. Structuralist critics (most notably Richard Lewontin and Stephen Jay Gould in their "spandrel" paper) contend that the adaptationists have overemphasized the power of natural selection to shape individual traits to an evolutionary optimum. Adaptationists are sometimes accused by their critics of using ad hoc"just-so stories". The critics, in turn, have been accused of misrepresentation (Straw man argumentation), rather than attacking the actual statements of supposed adaptationists.
Adaptationist researchers respond by asserting that they, too, follow George Williams'
depiction of adaptation as an "onerous concept" that should only be
applied in light of strong evidence. This evidence can be generally
characterized as the successful prediction of novel phenomena based on
the hypothesis that design details of adaptations should fit a complex
evolved design to respond to a specific set of selection pressures. In
evolutionary psychology, researchers such as Leda Cosmides, John Tooby, and David Buss
contend that the bulk of research findings that were uniquely predicted
through adaptationist hypothesizing comprise evidence of the methods'
validity.
Purpose and function
There are philosophical issues with the way biologists speak of
function, effectively invoking teleology, the purpose of an adaptation.
To say something has a function is to say something about what it
does for the organism. It also says something about its history: how it
has come about. A heart
pumps blood: that is its function. It also emits sound, which is
considered to be an ancillary side-effect, not its function. The heart
has a history (which may be well or poorly understood), and that history
is about how natural selection formed and maintained the heart as a
pump. Every aspect of an organism that has a function has a history.
Now, an adaptation must have a functional history: therefore we expect
it must have undergone selection caused by relative survival in its
habitat. It would be quite wrong to use the word adaptation about a
trait which arose as a by-product.
Teleology was introduced into biology by Aristotle
to describe the adaptedness of organisms. Biologists have found the
implications of purposefulness awkward as they suggest supernatural
intention, an aspect of Plato's thinking which Aristotle rejected. A similar term, teleonomy, grew out of cybernetics and self-organising systems and was used by biologists of the 1960s such as Ernst Mayr and George C. Williams as a less loaded alternative.
On the one hand, adaptation is obviously purposeful: natural selection
chooses what works and eliminates what does not. On the other hand,
biologists want to deny conscious purpose in evolution. The dilemma gave
rise to a famous joke by the evolutionary biologist Haldane: "Teleology is like a mistress to a biologist: he cannot live without her but he's unwilling to be seen with her in public.'" David Hull
commented that Haldane's mistress "has become a lawfully wedded wife.
Biologists no longer feel obligated to apologize for their use of
teleological language; they flaunt it. The only concession which they
make to its disreputable past is to rename it 'teleonomy'."
Prenatal screening
focuses on finding problems among a large population with affordable
and noninvasive methods. Prenatal diagnosis focuses on pursuing
additional detailed information once a particular problem has been
found, and can sometimes be more invasive. The most common screening
procedures are routine ultrasounds, blood tests, and blood pressure measurement. Common diagnosis procedures include amniocentesis and chorionic villus sampling.
In some cases, the tests are administered to determine if the fetus
will be aborted, though physicians and patients also find it useful to
diagnose high-risk pregnancies early so that delivery can be scheduled
in a tertiary care hospital where the baby can receive appropriate care.
Prenatal testing in recent years has been moving towards
non-invasive methods to determine the fetal risk for genetic disorders.
The rapid advancement of modern high-performance molecular technologies
along with the discovery of cell-free fetal DNA (cffDNA) in maternal plasma has led to new methods for the determination of fetal chromosomal aneuploidies. This type of testing is referred to as non-invasive prenatal testing
(NIPT) or as non-invasive prenatal screening. Invasive procedures
remain important, though, especially for their diagnostic value in
confirming positive non-invasive findings and detecting genetic
disorders. Birth defects have an occurrence between 1 and 6%.
Purpose
There
are three purposes of prenatal diagnosis: (1) to enable timely medical
or surgical treatment of a condition before or after birth, (2) to give
the parents the chance to abort a fetus with the diagnosed condition,
and (3) to give parents the chance to prepare psychologically, socially,
financially, and medically for a baby with a health problem or
disability, or for the likelihood of a stillbirth. Prior information
about problems in pregnancy means that healthcare staff as well as
parents can better prepare themselves for the delivery of a child with a
health problem. For example, Down syndrome is associated with cardiac
defects that may need intervention immediately upon birth.
Determining if a parent carries specific genes associated with certain (primarily autosomal recessive) conditions
Very low risk, however there is the potential for bruising, pain,
nerve damage, fainting, haematoma, bacterial infection, and bloodborne
pathogen exposure.
Cell-free fetal DNA (cfDNA) Test/Noninvasive prenatal test (NIPT) (screen)
Week 10 – onward
Less invasive
Blood draw
~1–2 weeks
Gender, chromosomal abnormalities
Very low risk, however there is the potential for bruising, pain,
nerve damage, fainting, haematoma, bacterial infection, and bloodborne
pathogen exposure.
Very low risk, however there is the potential for bruising, pain,
nerve damage, fainting, haematoma, bacterial infection, and bloodborne
pathogen exposure.
Alpha-fetoprotein (AFP)/modified sequential/multiple marker/quad/triple/maternal serum test (screen)
Weeks 14 – 22
Less invasive
Blood draw
~1–2 weeks
Maternal hormone levels, risk of gestational hypertension and preeclampsia, chromosome abnormalities, neural tube defects
Very low risk, however there is the potential for bruising, pain,
nerve damage, fainting, haematoma, bacterial infection, and bloodborne
pathogen exposure.
Second trimester screening (screen)
Week 15 – 22
Invasive
Ultrasound and multiple markers or quad screen blood draw
~1–2 weeks
Chromosomal abnormalities, neural tube defects, abdominal wall defects, heart defects, other major physical defects
Very low risk, however there is the potential for bruising, pain,
nerve damage, fainting, haematoma, bacterial infection, and bloodborne
pathogen exposure.
Maternal blood draw after ingestion of glucose drink
~1–2 days
To indicate the possibility of gestational diabetes
Very low risk, however there is the potential for bruising, pain,
nerve damage, fainting, haematoma, bacterial infection, and bloodborne
pathogen exposure.
Maternal blood draws before and after ingestion of glucose drink, requires fasting
~2–3 days
To properly diagnose gestational diabetes following an abnormal result from the glucose challenge screen
Very low risk, however there is the potential for bruising, pain,
nerve damage, fainting, haematoma, bacterial infection, and bloodborne
pathogen exposure.
Non-stress test
Week 28 – onward
Non-invasive
Abdominal contraction/Fetal heart rate belt
Immediately
Fetal heart rate vs movement, oxygen levels (indicating problems stemming from the placenta or umbilical cord), fetal distress
NA
Group B Strep Test
Week 36 – 38
Invasive
Vaginal swab
~1–2 days
Bacteria indicating Group B Strep
NA
Cervix dialation check
Week 37 – onward
Invasive
The doctor takes a manual measurement inside the cervix
Immediately
Signs or progress of dialation, prodromal labor
Infection, premature rupture of amniotic membrane
External fetal monitoring
During Labor, after rupture of amnioatic sac
Invasive
Spiral wire electrode attached to body part (typically the scalp) of fetus via cervical insertion
Fetal red blood cells in the mother's blood, fetomaternal hemorrhage
Very low risk, however there is the potential for bruising, pain,
nerve damage, fainting, haematoma, bacterial infection, and bloodborne
pathogen exposure.
Prenatal screening
Maternal serum screening
First-trimester maternal serum screening can check levels of free β-hCG, PAPP-A, intact or beta hCG, or h-hCG in the woman's serum, and combine these with the measurement of nuchal translucency (NT). Some institutions also look for the presence of a fetal nasalbone on the ultrasound.
Second-trimester maternal serum screening (AFP screening, triple screen, quad screen, or penta screen) can check levels of alpha fetoprotein, β-hCG, inhibin-A, estriol, and h-hCG (hyperglycosolated hCG) in the woman's serum.
The triple test measures serum levels of AFP, estriol, and beta-hCG, with a 70% sensitivity and 5% false-positive rate. It is complemented in some regions of the United States, as the Quad test (adding inhibin A to the panel, resulting in an 81% sensitivity and 5% false-positive rate for detecting Down syndrome when taken at 15–18 weeks of gestational age).
The biomarkers PAPP-A and β-hCG
seem to be altered for pregnancies resulting from ICSI, causing a
higher false-positive rate. Correction factors have been developed and
should be used when screening for Down's syndrome in singleton
pregnancies after ICSI, but in twin pregnancies such correction factors have not been fully elucidated. In vanishing twin
pregnancies with a second gestational sac with a dead fetus,
first-trimester screening should be based solely on the maternal age and
the nuchal translucency scan as biomarkers are altered in these cases.
Advances in prenatal screening
Measurement of fetal proteins in maternal serum is a part of standard prenatal screening for fetal aneuploidy and neural tube defects.
Computational predictive model shows that extensive and diverse
feto-maternal protein trafficking occurs during pregnancy and can be
readily detected non-invasively in maternal whole blood.
This computational approach circumvented a major limitation, the
abundance of maternal proteins interfering with the detection of fetal
proteins, to fetal proteomic analysis of maternal blood. Entering fetal
gene transcripts previously identified in maternal whole blood into a
computational predictive model helped develop a comprehensive proteomic
network of the term neonate. It also shows that the fetal proteins
detected in pregnant woman's blood originate from a diverse group of
tissues and organs from the developing fetus. Development proteomic
networks dominate the functional characterization of the predicted
proteins, illustrating the potential clinical application of this
technology as a way to monitor normal and abnormal fetal development.
The difference in methylation
of specific DNA sequences between mother and fetus can be used to
identify fetal-specific DNA in the blood circulation of the mother. In a
study published in the March 6, 2011, online issue of Nature, using this non-invasive technique a group of investigators from Greece and UK achieved correct diagnosis of 14 trisomy 21 (Down syndrome) and 26 normal cases.Using massive parallel sequencing,
a study testing for trisomy 21 only, successfully detected 209 of 212
cases (98.6%) with 3 false-positives in 1,471 pregnancies (0.2%).
With commercially available non-invasive (blood) testing for Down
syndrome having become available to patients in the United States and
already available in China, in October 2011, the International Society
for Prenatal Diagnosis created some guidance. Based on its sensitivity and specificity,
it constitutes an advanced screening test and that positive results
require confirmation by an invasive test, and that while effective in
the diagnosis of Down syndrome, it cannot assess half the abnormalities
detected by invasive testing. The test is not recommended for general
use until results from broader studies have been reported, but may be
useful in high-risk patients in conjunction with genetic counseling.
A study in 2012 found that the maternal plasma cell-free DNA test
was also able to detect trisomy 18 (Edwards syndrome) in 100% of the
cases (59/59) at a false-positive rate of 0.28%, and trisomy 13 (Patau
syndrome) in 91.7% of the cases (11/12) at a false-positive rate of
0.97%. The test interpreted 99.1% of samples (1,971/1,988); among the 17
samples without an interpretation, three were trisomy 18. The study
stated that if z-score cutoffs for trisomy 18 and 13 were raised
slightly, the overall false-positive rates for the three aneuploidies
could be as low as 0.1% (2/1,688) at an overall detection rate of 98.9%
(280/283) for common aneuploidies (this includes all three trisomies:
Down, Edwards and Patau).
Prenatal genetic testing
The goal of prenatal genetic testing is to identify pregnancies at
high risk of abnormalities, allowing for early intervention, termination
or appropriate management and preparation measures.
Prenatal genetic testing can be subdivided into two categories:
screening and diagnostic testing. Screening informs an individual of the
potential for certain abnormalities occurring, whereas, diagnostic
testing is used to confirm/diagnose that specific abnormalities exist
within the fetus. Prenatal screens are typically less invasive than
prenatal diagnostic tests. Screening comes with much lower risks,
however, the results are not as definitive as diagnostic tests.
Providers often recommend following up with a diagnostic test upon
receipt of a positive result from a specific screen.
Medically invasive techniques are those in which a tool is used
to access something inside the body. There are varying degrees of
invasiveness, depending on what specimen is required to complete the
test. The typical blood draw administered by a healthcare professional
is one of the most common invasive medical practices.
Since it causes minimal discomfort and there is very low risk
associated with the sample collection, a blood draw is considered less
invasive. Chorionic villus sampling (CVS) and Amniocentesis are the most
invasive prenatal tests because there is greater associated risk and
the sample is more difficult to access. These procedures are done via
needle insertion into the abdomen to collect a sample within the uterus,
meaning exceptional care/precision is required.
Prenatal genetic testing can identify various chromosomal abnormalities,
autosomal conditions, various birth defects, and some fetal blood
disorders.
Chromosomal abnormalities
are when the chromosomes differ in either structure or number when
compared to a typical reference genome. This includes chromosomal
deletions, duplications, inversions, and translocations. Some examples of chromosomal abnormalities include:
Autosomal recessive conditions occur when both parents pass on a mutation within an autosomal (non-sex) chromosome. Some examples of autosomal recessive conditions are:
Neural tube defects
are a type of birth defect that occurs when the neural tube of a fetus
does not form/close properly, potentially effecting other systems
throughout the body. Some examples of neural tube defects are:
Abdominal wall defects
are a type of birth defect that occur when the abdominal wall of a
fetus does not form properly, potentially effecting other organs
throughout the body. Some examples of abdominal wall defects are:
Blood disorders can occur from a negative interaction between the maternal blood and the fetal blood. An example of a fetal blood disorder is Hemolytic disease of the fetus.
Ultrasound imaging and serum markers as indications for genetic testing
Ultrasound
imaging provides the opportunity to conduct a nuchal translucency (NT)
scan screening for chromosomal abnormalities such as Down syndrome (trisomy 21), Edwards syndrome (trisomy 18), and Patau syndrome
(trisomy 13). Using the information from the NT scan the mother can be
offered an invasive diagnostic test for fetal chromosomal abnormalities.
Serum markers are used in a similar fashion to identify gestations that
should be recommended for further testing. When the NT scan or serum
markers arouse suspicion for chromosomal abnormalities the following
genetic tests may be conducted on fetal or placental tissue samples:
Interphase-fluorescence in situ hybridization (FISH), quantitative PCR and direct preparation of chromosomes from chorionic villi.
Screens
Carrier screening
Carrier
screening is a general DNA test that uses a blood or cheek swab sample
to determine if the parents carry certain genetic conditions. This test
can be done anytime, whether the individual(s) are considering starting a
family or have already become pregnant. Various types of carrier
screens are available that test for progressively more genetic
abnormalities. The single gene/condition screen will test for a specific
condition, whereas, the expanded carrier screen will test for hundreds
of different abnormalities that can be inherited by a fetus. There are
also three gene/condition and ethnic specific carrier tests. In the case
of a positive test result, further testing is often recommended, as the
carrier test only determines if the parent(s) is a carrier, not if the
gene has definitively been passed to the fetus.
Placental acellular DNA (pa-DNA)
Placental
acellular (fetal cell-free) DNA testing (pa-DNA) allows for the
detection of apoptotic placental cells and placental DNA circulating in
maternal blood for the noninvasive diagnosis of fetal aneuploidy.
A meta-analysis that investigated the success rate of using placental
acellular DNA from maternal blood to screen for aneuploidies found that
this technique detected trisomy 13 in 99% of the cases, trisomy 18 in
98% of the cases and trisomy 21 in 99% of the cases.
Failed tests using placental acellular DNA are more likely to occur in
fetuses with trisomy 13 and trisomy 18 but not with trisomy 21.
Previous studies found elevated levels of acellular placental DNA for
trisomy 13 and 21 from maternal serum when compared to women with
euploid pregnancies. However, an elevation of acellular DNA for trisomy 18 was not observed.
Circulating placental nucleated cells comprise only three to six
percent of maternal blood plasma DNA, reducing the detection rate of
fetal developmental abnormalities. Two alternative approaches have been developed for the detection of fetal aneuploidy. The first involves the measuring of the allelic ratio of single nucleotide polymorphisms (SNPs) in the mRNA coding region in the placenta. The next approach is analyzing both maternal and placental DNA and looking for differences in the DNA methylation patterns.
First/Second/Third trimester Screen
The
first, second, combined, and third trimester screens typically consist
of an ultrasound (abdominal and/or transvaginal) and maternal
blood/serum testing. The ultrasound is used to visually assess the
growth, development, and activity of the fetus through imaging
observations and measurements. The ultrasound portion of the first
trimester screen can include a nuchal translucency screen and a fetal
nasal bone determination screen. The available blood tests from the
first trimester screen can test for plasma protein A and human chorionic
gonadotropin. The second trimester screen looks at specific blood
markers, to include the estriol, inhibin and human chorionic
gonadotropin hormones and often consists of Alpha-fetoprotein (AFP)
screening. Any abnormal results from these screening tests can indicate
the possibility of abnormal conditions such as Trisomy 18, Trisomy 21
(Down syndrome), and spina bifida.
Alpha-fetoprotein (AFP)/multiple marker test
The
AFP test is often done in the second trimester using the serum from the
maternal blood draw. This test looks at a specific protein that is
formed in the liver of the fetus and released into the fluid contents of
the womb, which is then absorbed into the mother's blood stream.
Multiple determinations stem from the results of AFP testing.
Genetically, it can expose chromosomal and neural defects.
Diagnostic tests
Chorionic Villus Sampling (CVS)
CVS
is an invasive diagnostic test that can be done during the first
trimester of pregnancy for individuals that are looking to identify or
are at higher risk of passing chromosomal abnormalities. A tissue cell
sample of the placenta is obtained abdominally via needle or via vaginal
insertion of a catheter/syringe into the cervix in combination with
ultrasound to guide the procedure. Positive results from CVS require
blood testing for confirmation.
Amniocentesis
Amniocentesis
is an invasive diagnostic test that can be done during the second
trimester of pregnancy for individuals that are looking to identify or
are at higher risk of passing chromosomal and/or neural tube
abnormalities. The procedure is typically done via needle, in
combination with ultrasound for guidance, to obtain a sample of the
amniotic fluid surrounding the fetus.
PUBS
is an invasive diagnostic test that can be done during the second
trimester of pregnancy for individuals that are looking to identify or
are at higher risk of passing chromosomal and/or blood abnormalities.
The demand for cordocentesis tests is diminishing because it has been
replaced with CVS and Amniocentesis, which carry less risk. The
procedure is typically done via needle into the mother's abdomen, in
combination with ultrasound for guidance, to obtain a blood sample from
the umbilical cord of the fetus.
Prenatal genetic testing analysis techniques
Digital PCR
Recently, it has been proposed that digital PCR
analysis can be conducted on fetal cell-free DNA for detection of fetal
aneuploidy. Research has shown that digital PCR can be used to
differentiate between normal and aneuploid DNA.
A variation of the PCR technique called multiplex ligation-dependent probe amplification (MLPA), targeting DNA, has been successively applied for diagnosing fetal aneuploidy as a chromosome- or gene-specific assay.
Shotgun sequencing
Fetal cell-free DNA has been directly sequenced using shotgun sequencing
technology. In one study, DNA was obtained from the blood plasma of
eighteen pregnant women. This was followed by mapping the chromosome
using the quantification of fragments. This was done using advanced
methods in DNA sequencing
resulting in the parallel sequencing of the fetal DNA. The amount of
sequence tags mapped to each chromosome was counted. If there was a
surplus or deficiency in any of the chromosomes, this meant that there
was a fetal aneuploid. Using this method of shotgun sequencing, the
successful identification of trisomy 21 (Down syndrome), trisomy 18
(Edward syndrome), and trisomy 13 (Patau syndrome) was possible. This
method of noninvasive diagnosis is now starting to be heavily used and
researched further.
Other techniques
Microarray
analysis, karyotyping, and different genome sequencing techniques are
also used to detect abnormalities. Fetal components in samples from
maternal blood plasma can be analyzed by genome-wide techniques not only
by total DNA, but also by methylated DNA immunoprecipitation (with tiling array), microRNA (such as with Megaplex) and total RNA (RNA-sequencing).
By invasiveness
Amniocentesis is an example of an invasive diagnostic prenatal test.
Diagnostic prenatal testing can be performed by invasive or non-invasive methods. An invasive method involves probes or needles being inserted into the uterus, e.g. amniocentesis, which can be done from about 14 weeks gestation, and usually up to about 20 weeks, and chorionic villus sampling,
which can be done earlier (between 9.5 and 12.5 weeks gestation) but
which may be slightly more risky to the fetus. One study comparing
transabdominal chorionic villus sampling with second trimester
amniocentesis found no significant difference in the total pregnancy
loss between the two procedures. However, transcervical
chorionic villus sampling carries a significantly higher risk, compared
with a second-trimester amniocentesis, of total pregnancy loss (relative risk 1.40; 95% confidence interval 1.09 to 1.81) and spontaneous miscarriage (9.4% risk; relative risk 1.50; 95% confidence interval 1.07 to 2.11).
Ultrasonography is an example of a non-invasive diagnostic prenatal test.
Non-invasive techniques include examinations of the woman's womb through ultrasonography and maternal serum screens (i.e. Alpha-fetoprotein).
Blood tests for select trisomies (Down syndrome in the United States,
Down and Edwards syndromes in China) based on detecting cell-free placental DNA present in maternal blood, also known as non-invasive prenatal testing (NIPT), have become available.
If an elevated risk of chromosomal or genetic abnormality is indicated
by a non-invasive screening test, a more invasive technique may be
employed to gather more information. In the case of neural tube defects, a detailed ultrasound can non-invasively provide a definitive diagnosis.
One of the major advantages of the non-invasive prenatal testing
is that the chance of a false positive result is very low. This accuracy
is very important for the pregnant woman, as due to a high sensitivity
and specificity of the testing, especially for Down syndrome, the
invasive testing could be avoided, which includes the risk of a
miscarriage.
Testing guidelines and qualifying risk factors for invasive testing
The American College of Obstetricians and Gynecologists (ACOG)
guidelines currently recommend that anyone who is pregnant, regardless
of age, should discuss and be offered non-invasive prenatal genetic
screening and diagnostic testing options.
Non-invasive prenatal genetic screening is typically performed at the
end of the 1st trimester (11–14 weeks) or during the beginning of the
second trimester (15–20 weeks). This involves the pregnant woman
receiving a blood draw with a needle and a syringe and an ultrasound of
the fetus. Screening tests can then include serum analyte screening or cell-free fetal DNA, and nuchal translucency ultrasound [NT], respectively.
It is important to note that screening tests are not diagnostic, and
concerning screening results should be followed up with invasive
diagnostic testing for a confirmed diagnosis. Invasive diagnostic
prenatal genetic testing can involve chronic villus sampling (CVS) or amniocentesis. The ACOG recommends genetic screening before pregnancy to all pregnant women planning to have a family.
After comprehensive counseling and discussion that acknowledges
residual risks, it is important to respect the patients' right of
choosing whether or not to pursue any component of genetic testing.
The following are some reasons why a woman might consider her
risk of birth defects already to be high enough to warrant skipping
screening and going straight for invasive testing:
Increased risk of fetal aneuploidy based on personal obstetric history or family history affected by aneuploidy
Increased risk for a known genetic or biochemical disease of the fetus
Maternal transmissible infectious disease such as rubella or toxoplasma
Parental request in the context of acute parental anxiety or under exceptional circumstances
Patient acceptance
Research
was conducted to determine how women felt about noninvasive diagnosis
of fetal aneuploid using maternal blood. This study was conducted using
surveys. It was reported that eighty-two percent of pregnant women and
seventy-nine percent of female medical students view this type of
diagnosis in a positive light, agreeing that it is important for
prenatal care. Overall, women responded optimistically that this form of
diagnosis will be available in the future.
Examination of the woman's uterus from outside the body. The uterus is commonly palpated to determine if there are problems with the position of the fetus (i.e. breech position). Fundal height may also be measured.
Commonly dating scans (sometimes known as booking scans or dating ultrasounds) from 7 weeks to confirm pregnancy dates and look for multiple pregnancies. The specialised nuchal scan at 11–13 weeks may be used to identify higher risks of Downs syndrome. Later morphology scans, also called anatomy ultrasound,
from 18 weeks may check for any abnormal development. Additional
ultrasounds may be performed if there are any other problems with the
pregnancy, or if the pregnancy is post-due.
First or second trimester
Non-invasive
Fetal heartbeat
Listening to the fetal heartbeat via an external monitor placed on the outside of the abdomen.
Use of cardiotocography during the third trimester to monitor fetal wellbeing.
Third trimester
Non-invasive
Maternal blood pressure
Used to screen for pre-eclampsia throughout the pregnancy.
First, second and third trimester
Non-invasive
Maternal weighing
Unusually low or high maternal weight can indicate problems with the pregnancy.
First, second and third trimesters.
Less invasive
Fetal cells in maternal blood (FCMB)
Requires a maternal blood draw. Based on enrichment of fetal cells
which circulate in maternal blood. Since fetal cells hold all the
genetic information of the developing fetus, they can be used to perform
prenatal diagnosis.
Requires a maternal blood draw. Based on DNA of fetal origin
circulating in the maternal blood. Testing can potentially identify
fetal aneuploidy
(available in the United States, beginning 2011) and gender of a fetus
as early as six weeks into a pregnancy. Fetal DNA ranges from about
2–10% of the total DNA in maternal blood.
Cell-free fetal DNA also allows whole genome sequencing of the fetus, thus determining the complete DNA sequence of every gene.
Involves getting a sample of the chorionic villus and testing it. This can be done earlier than amniocentesis, but may have a higher risk of miscarriage, estimated at 1%.
This can be done once enough amniotic fluid
has developed to sample. Cells from the fetus will be floating in this
fluid, and can be separated and tested. Miscarriage risk of
amniocentesis is commonly quoted as 0.06% (1:1600). By amniocentesis it is also possible to cryopreserveamniotic stem cells.
Though rarely done, these involve putting a probe into a women's
uterus to observe (with a video camera), or to sample blood or tissue
from the embryo or fetus.
PUBS is a diagnostic genetic test that examines blood from the fetal umbilical cord to detect fetal abnormalities.
24–34 weeks
By pregnancy stage
Pre-conception
Prior
to conception, couples may elect to have genetic testing done to
determine the odds of conceiving a child with a known genetic anomaly.
The most common in the Caucasian population are:
Hundreds of additional conditions are known and more discovered on a
regular basis. However the economic justification for population-wide
testing of all known conditions is not well supported, particularly once
the cost of possible false positive results and concomitant follow-up
testing are taken into account. There are also ethical concerns related to this or any type of genetic testing.
One or both partners may be aware of other family members with
these diseases. Testing prior to conception may alleviate concern,
prepare the couple for the potential short- or long-term consequences of
having a child with the disease, direct the couple toward adoption or
foster parenting, or prompt for preimplantation genetic testing during in vitro fertilization. If a genetic disorder is found, professional genetic counseling
is usually recommended owing to the host of ethical considerations
related to subsequent decisions for the partners and potential impact on
their extended families. Most, but not all, of these diseases follow Mendelian inheritance patterns. Fragile X syndrome is related to expansion of certain repeated DNA segments and may change generation-to-generation.
First trimester
At early presentation of pregnancy at around 6 weeks, early dating ultrasound scan may be offered to help confirm the gestational age
of the embryo and check for a single or twin pregnancy, but such a scan
is unable to detect common abnormalities. Details of prenatal screening
and testing options may be provided.
Around weeks 11–13, nuchal translucency scan
(NT) may be offered which can be combined with blood tests for PAPP-A
and beta-hCG, two serum markers that correlate with chromosomal
abnormalities, in what is called the First Trimester Combined Test. The
results of the blood test are then combined with the NT ultrasound
measurements, maternal age, and gestational age of the fetus to yield a
risk score for Down syndrome, trisomy 18, and trisomy 13. First
Trimester Combined Test has a sensitivity (i.e. detection rate for
abnormalities) of 82–87% and a false-positive rate of around 5%.
Cell-free fetal DNA is also available during the first trimester of pregnancy.
A second-trimester Quad blood test may be taken (the Triple test is widely considered obsolete but in some states, such as Missouri, where Medicaid only covers the Triple test, that's what the patient typically gets). With integrated screening,
both a First Trimester Combined Test and a Triple/Quad test is
performed, and a report is only produced after both tests have been
analyzed. However patients may not wish to wait between these two sets
of tests. With sequential screening, a first report is produced
after the first trimester sample has been submitted, and a final report
after the second sample. With contingent screening, patients at
very high or very low risks will get reports after the first-trimester
sample has been submitted. Only patients with moderate risk (risk
score between 1:50 and 1:2000) will be asked to submit a
second-trimester sample, after which they will receive a report
combining information from both serum samples and the NT
measurement. The First Trimester Combined Test and the Triple/Quad test
together have a sensitivity of 88–95% with a 5% false-positive rate for
Down syndrome, though they can also be analyzed in such a way as to
offer a 90% sensitivity with a 2% false-positive rate. Finally, patients
who do not receive an NT ultrasound in the 1st trimester may still
receive a Serum Integrated test involving measuring PAPP-A serum levels
in the 1st trimester and then doing a Quad test in the 2nd trimester.
This offers an 85–88% sensitivity and 5% false-positive rate for Down
syndrome. Also, a patient may skip the 1st-trimester screening entirely
and receive only a 2nd-trimester Quad test, with an 81% sensitivity for
Down syndrome and 5% false-positive rate.
Third trimester
Third-trimester prenatal testing generally focuses on maternal wellbeing and reducing fetal morbidity/mortality. Group B streptococcal infection
(also called Group B strep) may be offered, which is a major cause of
neonatal morbidity and mortality. Group B strep is an infection that may
be passed to an infant during birth. Vaginal screening for GBS is
performed between 34 and 37 weeks of gestational age, so that mothers
that are positive for the bacterium can receive treatment before
delivery. During the third trimester, some institutions may require
evaluations of hemoglobin/hematocrit, syphilis serology, and HIV
screening. Also, before delivery, an assessment of fetal position and
estimated fetal weight is documented.
Legislation
In Europe
Prenatal
diagnosis (DPN) is permitted throughout Europe, with the exception of
Ireland. Eight (8) countries have no legislation on this matter.
However, there are differences between states. For instance, in Poland, the deadline for DPN is 22 weeks. In Malta,
the Parliamentary Social Affairs Committee specified in its 2005 report
that DPN should only be allowed for conditions for which therapeutic
options exist. Nevertheless, all countries prohibit DPN for non-medical
purposes (such as sex selection), for example.
In France
Article
L2131-1 of the Public Health Code, stemming from the July 2011
bioethics law, states that "prenatal diagnosis refers to medical
practices, including obstetric and fetal ultrasound, aimed at detecting,
in utero, a particularly severe condition in the embryo or fetus." The
law requires that pregnant women receive clear information about these
techniques to "assess the risk that the embryo or fetus may have a
condition that could alter the course or management of the pregnancy.
Parents
need to make informed decisions about screening, diagnosis, and any
actions to be taken as a result. Many screening tests are inaccurate, so
one worrisome test result frequently leads to additional, more invasive
tests. If prenatal testing confirms a serious disability, many parents
are forced to decide whether to continue the pregnancy or seek an
abortion. The "option" of screening becomes an unexpected requirement to
decide.
In some genetic conditions, for instance cystic fibrosis, an abnormality can only be detected if DNA is obtained from the fetus. Usually an invasive method is needed to do this.
Ultrasound of a fetus, which is considered a screening test, can
sometimes miss subtle abnormalities. For example, studies show that a
detailed 2nd-trimester ultrasound, also called a level 2 ultrasound, can
detect about 97% of neural tube defects such as spina bifida. Ultrasound results may also show "soft signs," such as an Echogenic intracardiac focus or a Choroid plexus cyst, which are usually normal, but can be associated with an increased risk for chromosome abnormalities.
Other screening tests, such as the Quad test, can also have false
positives and false negatives. Even when the Quad results are positive
(or, to be more precise, when the Quad test yields a score that shows at
least a 1 in 270 risk of abnormality), usually the pregnancy is normal,
but additional diagnostic tests are offered. In fact, consider that
Down syndrome affects about 1:400 pregnancies; if you screened 4000
pregnancies with a Quad test, there would probably be 10 Down syndrome
pregnancies of which the Quad test, with its 80% sensitivity, would call
8 of them high-risk. The quad test would also tell 5% (~200) of the
3990 normal women that they are high-risk. Therefore, about 208 women
would be told they are high-risk, but when they undergo an invasive
test, only 8 (or 4% of the high risk pool) will be confirmed as positive
and 200 (96%) will be told that their pregnancies are normal. Since
amniocentesis has approximately a 0.5% chance of miscarriage, one of
those 200 normal pregnancies might result in a miscarriage because of
the invasive procedure. Meanwhile, of the 3792 women told they are
low-risk by the Quad test, 2 of them will go on to deliver a baby with
Down syndrome. The Quad test is therefore said to have a 4% positive predictive value
(PPV) because only 4% of women who are told they are "high-risk" by the
screening test actually have an affected fetus. The other 96% of the
women who are told they are "high-risk" find out that their pregnancy is
normal.
By comparison, in the same 4000 women, a screening test that has a
99% sensitivity and a 0.5% false positive rate would detect all 10
positives while telling 20 normal women that they are positive.
Therefore, 30 women would undergo a confirmatory invasive procedure and
10 of them (33%) would be confirmed as positive and 20 would be told
that they have a normal pregnancy. Of the 3970 women told by the screen
that they are negative, none of the women would have an affected
pregnancy. Therefore, such a screen would have a 33% positive predictive
value.
The real-world false-positive rate for the Quad test (as well as
1st Trimester Combined, Integrated, etc.) is greater than 5%. 5% was the
rate quoted in the large clinical studies that were done by the best
researchers and physicians, where all the ultrasounds were done by
well-trained sonographers and the gestational age of the fetus was
calculated as closely as possible. In the real world, where calculating
gestational age may be a less precise art, the formulas that generate a
patient's risk score are not as accurate and the false-positive rate can
be higher, even 10%.
Because of the low accuracy of conventional screening tests,
5–10% of women, often those who are older, will opt for an invasive test
even if they received a low-risk score from the screening. A patient
who received a 1:330 risk score, while technically low-risk (since the
cutoff for high-risk is commonly quoted as 1:270), might be more likely
to still opt for a confirmatory invasive test. On the other hand, a
patient who receives a 1:1000 risk score is more likely to feel assuaged
that her pregnancy is normal.
Both false positives and false negatives will have a large impact on a couple when they are told the result, or when the child is born. Diagnostic
tests, such as amniocentesis, are considered to be very accurate for
the defects they check for, though even these tests are not perfect,
with a reported 0.2% error rate (often due to rare abnormalities such as
mosaic Down syndrome where only some of the fetal/placental cells carry
the genetic abnormality).
A higher maternal serum AFP
level indicates a greater risk for anencephaly and open spina bifida.
This screening is 80% and 90% sensitive for spina bifida and
anencephaly, respectively.
Many maternal-fetal specialists do not bother to even do an AFP
test on their patients because they do a detail ultrasound on all of
them in the 2nd trimester, which has a 97% detection rate for neural
tube defects such as anencephaly and open spina bifida. Performing tests
to determine possible birth defects is mandatory in all U.S. states. Failure to detect issues early can have dangerous consequences on both the mother and the baby. OBGYNs
may be held culpable. In one case a man who was born with spina bifida
was awarded $2 million in settlement, apart from medical expenses, due
to the OBGYN's negligence in conducting AFP tests.
No prenatal test can detect all forms of birth defects and abnormalities.
Prenatal genetic testing
Another
important issue is the uncertainty of prenatal genetic testing.
Uncertainty on genetic testing results from several reasons: the genetic
test is associated with a disease but the prognosis and/or probability
is unknown, the genetic test provides information different than the
familiar disease they tested for, found genetic variants have unknown
significance, and finally, results may not be associated with found
fetal abnormalities.
Richardson and Ormond thoroughly addressed the issue of uncertainty of
genetic testing and explained its implication for bioethics. First, the
principle of beneficence is assumed in prenatal testing by decreasing
the risk of miscarriage, however, uncertain information derived from
genetic testing may harm the parents by provoking anxiety and leading to
the termination of a fetus that is probably healthy. Second, the
principle of autonomy is undermined given a lack of comprehension
resulting from new technologies and changing knowledge in the field of
genetics. And third, the principle of justice raised issues regarding
equal access to emerging prenatal tests.
Availability of treatments
If
a genetic disease is detected, there is often no treatment that can
help the fetus until it is born. However, in the US, there are prenatal
surgeries for spina bifida fetus. Early diagnosis gives the parents time to research and discuss post-natal treatment and care, or in some cases, abortion. Genetic counselors are usually called upon to help families make informed decisions regarding results of prenatal diagnosis.
Patient education
Researchers have studied how disclosing amniocentesis or chorionic villous sampling
(CVS) results on a fixed date versus a variable date (i.e. "when
available") affects maternal anxiety. Systematic review of the relevant
articles found no conclusive evidence to support issuing amniocentesis
results as soon as they become available (in comparison to issuing
results on a pre-defined fixed date). The researchers concluded that
further studies evaluating the effect of different strategies for
disclosing CVS results on maternal anxiety are needed.
Concerns from disability rights activists and scholars
Disability
rights activists and scholars have suggested a more critical view of
prenatal testing and its implications for people with disabilities. They
argue that there is pressure to abort fetuses that might be born with
disabilities, and that these pressures rely on eugenics interests and
ableist stereotypes.
This selective abortion relies on the ideas that people with
disabilities cannot live desirable lives, that they are "defective," and
that they are burdens, while disability scholars argue that "oppression
is what's most disabling about disability." Marsha Saxton suggests that
women should question whether or not they are relying on real, factual
information about people with disabilities or on stereotypes if they
decide to abort a fetus with a disability.
Societal pressures
Amniocentesis
has become the standard of care for prenatal care visits for women who
are "at risk" or over a certain age. The wide use of amniocentesis has
been defined as consumeristic. and some argue that this can be in conflict with the right to privacy, Most obstetricians (depending on the country) offer patients the AFP triple test, HIV test, and ultrasounds routinely. However, almost all women meet with a genetic counselor
before deciding whether to have prenatal diagnosis. It is the role of
the genetic counselor to accurately inform women of the risks and
benefits of prenatal diagnosis. Genetic counselors are trained to be
non-directive and to support the patient's decision. Some doctors do
advise women to have certain prenatal tests and the patient's partner
may also influence the woman's decision.
Legal
In
August 2023, the Iranian government banned import and manufacture of
tests kits required for first screening trimester tests, it will plague
the population according to society of medicine in genetic انجمن ژنتیک پزشکی ایران [fa]. Iranian state welfare organization had a genetics condition program since 1997.
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