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Tay–Sachs disease
Synonyms GM2 gangliosidosis, hexosaminidase A deficiency
Tay-sachsUMich.jpg
Cherry-red spot as seen in the retina in Tay–Sachs disease. The fovea's center appears bright red because it is surrounded by a whiter than usual area.
Specialty Medical genetics
Symptoms Initially: Decreased ability to turn over, sit, or crawl
Later: Seizures, hearing loss, inability to move
Usual onset Three to six months of age
Duration Long term
Types Infantile, juvenile, late-onset
Causes Genetic (autosomal recessive)
Diagnostic method Testing blood hexosaminidase A levels, genetic testing
Differential diagnosis Sandhoff disease, Leigh syndrome, neuronal ceroid lipofuscinoses
Treatment Supportive care, psychosocial support
Prognosis Death often occurs in early childhood
Frequency Rare in the general population

Tay–Sachs disease is a genetic disorder that results in the destruction of nerve cells in the brain and spinal cord. The most common type, known as infantile Tay–Sachs disease, becomes apparent around three to six months of age with the baby losing the ability to turn over, sit, or crawl. This is then followed by seizures, hearing loss, and inability to move. Death usually occurs in early childhood. Less commonly the disease may occur in later childhood or adulthood. These forms are generally milder in nature.

Tay–Sachs disease is caused by a genetic mutation in the HEXA genes on chromosome 15. It is inherited from a person's parents in an autosomal recessive manner. The mutation results in problems with an enzyme called beta-hexosaminidase A which results in the buildup of the molecule GM2 ganglioside within cells, leading to toxicity. Diagnosis is by measuring the blood hexosaminidase A level or genetic testing. It is a type of sphingolipidosis.

The treatment of Tay–Sachs disease is supportive in nature. This may involve multiple specialities as well as psychosocial support for the family. The disease is rare in the general population. In Ashkenazi Jews, French Canadians of southeastern Quebec, and Cajuns of southern Louisiana, the condition is more common. Approximately 1 in 3,600 Ashkenazi Jews at birth are affected.

The disease is named after Waren Tay, who in 1881 first described a symptomatic red spot on the retina of the eye; and Bernard Sachs, who described in 1887 the cellular changes and noted an increased rate of disease in Ashkenazi Jews. Carriers of a single Tay–Sachs allele are typically normal. It has been hypothesized that being a carrier may confer protection from another condition such as tuberculosis, explaining the persistence of the allele in certain populations. Researchers are looking at gene therapy or enzyme replacement therapy as possible treatments.

Signs and symptoms