||Potentially 1 in 3,600 in the Ashkenazi Jewish population; frequency decreased through success of carrier screening programs
||1 in 26 to 1 in 30 in Ashkenazi Jews, 1 in 300 in non-Jewish population
What is Tay-Sachs disease?
Tay-Sachs disease (TSD) is the most familiar of the Jewish genetic disorders. It is caused by a deficiency of an enzyme called hexosaminidase A, or hex A. Lack of this enzyme affects the brain and the nervous system, causing rapid and progressive deterioration. Death usually occurs by the age of 6. A late-onset form of Tay-Sachs also occurs, although it is rare.
What are the symptoms?
Babies with Tay-Sachs disease are normal at birth. However, at 3 to 6 months of age, an affected baby will begin to lose developmental skills and experience progressive weakness, loss of motor skills, increased startle response and myoclonic jerks. A cherry red spot can appear in the eye. Within a few months the child begins to lose visual attentiveness, has decreased voluntary movements and responsiveness, and develops seizures. The disease progresses rapidly until the child becomes completely unresponsive.
Late-onset Tay-Sachs disease is caused by mutations in the same gene as classical infantile Tay-Sachs disease, but because an individual’s body retains some enzyme activity, the disease is less severe, though still difficult. There are three forms, the distinctions between which are not clearly delineated, leading to some overlap between types.
Juvenile onset: Onset occurs between 2 and 10 years of age. These patients can live up to late childhood or adolescence. The symptoms are the same as those seen in classical TSD but occur at an older age and often progress more slowly. Optic atrophy and progressive blindness are often seen, whereas the cherry red spot may not be.
Chronic onset: Age of onset ranges from early childhood to 10 years. The patients often have neurological speech and movement disorders and a wide-based, unsteady gait. It may be mistaken for spinocerebellar ataxia, Friedreich ataxia or amyotrophic lateral sclerosis. Progression is slow and lifespan is variable.
Adult onset: Age of onset is in adulthood. Patients may present with muscle wasting, weakness, involuntary twitches and motor speech disorders. It may be mistaken for spinal muscular atrophy or early-onset amyotrophic lateral sclerosis. Up to 40% of patients have psychiatric manifestations such as recurrent psychotic depression, bipolar symptoms and schizophrenia. It may be associated with dementia. Progression is slow and lifespan is variable.
Is there treatment available?
There is no effective treatment for Tay-Sachs disease at this time. Supportive care is aimed at providing the affected child with comfort. Research on Tay-Sachs disease is ongoing. Visit ClinicalTrials.gov for more information.
What is the life expectancy of someone with Tay-Sachs disease?
For individuals with classic Tay-Sachs disease, death usually occurs by 2 to 4 years of age from bronchopneumonia.
How do I find out if I am a carrier?
DNA testing can reveal approximately 98% of relevant mutations in the HEXA gene in the Ashkenazi population. An assay to assess the level of hexA enzyme may also be used to detect carriers of any ethnicity. Visit Screening and Counseling to learn more. The Center encourages prospective parents to meet with a genetic counselor and get tested before conception, in order to make the best health care decisions for their families.
How is Tay-Sach disease diagnosed?
A laboratory test checks for a lack of beta-hexosaminidase A (HEX A) enzymatic activity. Genetic testing can also check for relevant mutations in the HEXA gene. Both are done through a simple blood test.
Is prenatal diagnosis available?
DNA testing is available for couples with an affected child or to couples found to be at risk by carrier testing.
How can I find out more about Tay-Sachs disease?
National Tay-Sachs and Allied Disease Association
The mission of NTSAD is to lead the fight to treat and cure Tay-Sachs, Canavan and related genetic diseases and to support affected families and individuals in leading fuller lives. The site provides educational materials, information on the latest research, and many other resources for those affected by Tay-Sachs. There is also a New York area branch.
National Tay-Sachs and Allied Diseases Association of Delaware Valley
The Association provides in depth disease-specific information for both Tay-Sachs and Canavan diseases with the hope of educating and providing resources for those affected by either disease.
Canadian Association for Tay-Sachs and Allied Diseases
CATSAD is dedicated to the support of families of children with Tay-Sachs and allied diseases. The Association provides information and support services to individuals and families affected by these diseases and to the public at large.
Cure Tay-Sachs Foundation
The Cure Tay-Sachs Foundation focuses primarily on raising money for research. The site is a good resource for various research initiatives currently being explored.