brief description

Tay-Sachs disease is a fatal genetic disorder in children that causes the progressive destruction of the central nervous system. Due to a deficiency of a vital enzyme called hexosaminidase A (Hex-A), harmful quantities of a fatty substance called ganglioside GM2 accumulate in the nerve cells of the brain. As the nerve cells become distended with fatty materials, the cells become damaged and gradually lose their ability to function properly. The affected child fails to develop appropriate mental and motor functions.

Tay-Sachs is categorized as a lysosomal storage disease. Lysosomes are the major digestive units in cells. Enzymes within lysosomes break down or "digest" nutrients, including certain complex carbohydrates and fats.

Affected children show developmental abnormalities and delays during the first three to eight months of life. In the course of the disease, infants may have an exaggerated startle response to sudden noises, decreased eye contact, and exhibit listlessness. A "cherry-red spot" may be seen in the macula at the back of the eye.

The infant gradually regresses, losing previously acquired skills one by one (known as psychomotor regression). Muscle tone is diminished (hypotonia) and muscles become increasingly stiff. By about two years, most children experience recurrent seizures (uncontrolled electrical disturbances in the brain) and diminishing mental function. Affected children also develop seizures which are not always controllable with anti-epileptic drugs after this time. Loss of swallowing function occurs progressively together with increased risk for aspiration and subsequent chest and lung infections. The child eventually becomes blind, paralyzed, and nonresponsive to his or her environment. There is progressive dependence on external support.


Presently there is no treatment and no cure for Tay-Sachs disease.

Researchers are working on a number of avenues including stem cell replacement through bone marrow transplant to alleviate some symptoms of the disease and lengthen the lifespan of affected children.

Even with the best of care, children with classical Tay-Sachs die between two to five years of life, usually due to pneumonia or other chest and lung infections, or respiratory compromise.

prenatal testing

Tay-Sachs disease is an inherited metabolic disorder. Both parents must be carriers in order to have an affected child. Carrier couples have a 25% chance with each pregnancy of conceiving a child with that condition. There is a 50% chance of producing a child who is a carrier like the parents and a 25% chance that the child will be neither a carrier nor affected with the disease.

Carrier couples need time to review their options and make the necessary decisions about planning and protecting their families. We strongly recommend reviewing your options with a genetic counselor before getting pregnant.

Prenatal tests can diagnose Tay-Sachs disease before birth. For more information about the available options and our personal experience with prenatal testing, please go the prenatal testing page.

carrier screening

Tay-Sachs disease is an inherited metabolic disorder. Both parents must be carriers in order to have an affected child. Carrier screening and genetic counseling have made this disease rare in those at known risk.

Populations known to be at higher risk include people of Askenazic Jewish (Central or Eastern European), French-Canadian, and Cajun descent (1 in 27). Current research also estimates the carrier rate may be higher in Irish Americans, around 1 in 50 people. While there are certain populations at higher risk, anyone can be a carrier of Tay-Sachs.  Today, most patients are seen in families with no prior history of the disease, because the recessive gene can be carried without being expressed through many generations.

Patients and carriers of Tay-Sachs disease can be identified by a simple blood test that measures hexosaminidase A activity.

There are 2 types of tests for Tay-Sachs: enzyme assay or DNA studies.

1) The enzyme assay is a biochemical test that measures the level of Hex-A in a person's blood serum, in plasma or white blood cells. Carriers have less Hex-A in their body fluid and cells than non-carriers. Babies with infantile Tay-Sachs disease have a total absence of Hex-A in their cells.

2) DNA-based carrier testing looks for specific mutations in the gene that codes for Hex-A. Since 1985, when the Hex-A gene was isolated, over 50 different mutations in this gene have been identified. The limitation of DNA-based carrier testing is that not all known mutations in the Hex-A gene are detected by the test, as others have yet to be identified. The tests currently detect about 95% of carriers of Ashkenazi background and about 60% of non-Jewish individuals. Therefore, some people who are carriers will not be identified by DNA analysis alone.

*The information expressed here was taken from several sources including: What Every Family Should Know (NTSAD-1996), Rudolph's Pediatrics-20 ed. (1996), National Institute of Neurological Disorders and Stroke Fact Sheet on Tay-Sachs Disease (2000), and information from the National Organization for Rare Disorders (2000).


NTSAD Association is a non-profit, voluntary health organization that was founded in 1956. Programs include community education, carrier screening, international laboratory quality control, and family services.


2001 Beacon Street, Suite 204

Boston, Massachusetts 02135 USA

Tel. 617-277-4463 or 1-800-90-NTSAD

other helpful links

Further information is available from these organizations (last updated May, 2001):

Tay-Sachs Disease Information Sheet

Published by the March of Dimes Birth Defects Foundation, tel.1-800-367-6630. This site contains additional information about prenatal testing.

National Institute of Neurological Disorders and Stroke (NINDS)

Succinct fact sheet published by the National Institutes of Health. This site contains a short list of medical references for Tay-Sachs Disease.

Rare Genetic Diseases in Children: Resource Directory

Alliance of Genetic Support Groups: tel. 1-800-336-4363


Desnick, Robert J. and Michael M. Kaback (eds.). Tay Sachs Disease. Academic Press, 2001.

Scriver, Charles et al. Metabolic and Molecular Bases of Inherited Disease, 7th ed., McGraw Hill Inc.,1995.


1998. "Carrier Screening for Cystic Fibrosis, Gaucher Disease, and Tay-Sachs Disease in the Ashkenazi Jewish Population: The first 1000 cases at New York University Medical Center, New York, NY." David Kronn et al., Arch Intern Med, vol. 158: 777-781.

1996. "Twenty-Year Outcome Analysis of Genetic Screening Programs for Tay-Sachs and ß-Thalassemia Disease Carriers in High Schools." John Mitchell et al., American Journal of Human Genetics, vol. 59: 793-798.

1996. "Heterozygosity for Tay-Sachs Disease in non-Jewish Americans with ancestry from Ireland or Great Britain." Margaret van Bael et al., J Med Genet, vol. 33: 829-832. *This is the study that finds TSD rates for Irish Americans fall between 1 in 192 to 1 in 52.

1993. "Tay Sachs Disease - Carrier Screening, Prenatal Diagnosis, and the Molecular Era: An International Perspective, 1970 to 1993." Michael Kaback et al., JAMA Vol. 270, no. 19: 2307-2315. *The most comprehensive study that I have come across to date. Data collected through University of California, San Diego, from nearly 1,000,000 young adults of both Jewish and non-Jewish ancestry.


LOTS - Late Onset Tay Sachs Disease: tel. 1-800-672-2022

Tay-Sachs has three clinical forms: infantile, juvenile, and Late-Onset Tay-Sachs (LOTS). The juvenile and adult Late-Onset forms are much less common than the infantile form. Unlike the infantile form where there is no enzyme, some Hex-A enzyme activity is present in both juvenile and late-onset, but the levels are very low. Unfortunately, there is the same progressive deterioration of central nervous system, just at different ages.