Tay-Sachs disease is a fatal genetic disorder in which harmful quantities of a fatty substance called ganglioside GM2 accumulate in the nerve cells in the brain. The affected child appears to develop normally for the first few months of life. Then, as nerve cells become distended with fatty material, a relentless deterioration of mental and physical abilities occurs. Early symptoms become apparent within the first 3 to 6 months of life, with muscle weakness, blindness, psychomotor retardation, feeding difficulty, and general paralysis.
At about 18 months there are convulsions, progressive deafness, blindness, seizures, spasticity, and, ultimately, decerebrate rigidity. Anomalies of the face and head include doll-like facies, macrocephaly, translucent skin, long eyelashes, fine hair, and pale-pink coloration. Cherry red spots of the maculae are present in some cases. An almost total absence of the enzyme hexosaminidase (while hexosaminidase B activity is increased in the brain) is the most prominent biochemical feature of this syndrome.
Most affected children die from bronchopneumonia before the age of 3 years; survival beyond year 5 is extremely rare. The syndrome is transmitted as an autosomal recessive trait.
Tay-Sachs disease occurs predominantly, but not exclusively, in Jewish children of eastern and central European (Ashkenazi) families. Estimated occurrence in Ashkenazi-Jews in the U.S. is 400 per million births. Each sex is equally affected. About one out of every 30 American Jews carries the Tay-Sachs gene. Non-Jewish individuals of French-Canadian ancestry, including the Cajun population in Louisiana, are at similarly increased risk. Both groups have about 100 times the rate of occurrence of other ethnic groups. The juvenile form of Tay-Sachs, however, is not increased in these groups.
Patients and carriers of Tay-Sachs disease can be identified by a simple blood test that measures hexosaminidase. Both parents must be carriers in order to have an affected child. When both parents are found to carry a genetic mutation in hexosaminidase A, there is a 25 percent chance with each pregnancy that the child will be affected with Tay-Sachs disease.
Tay-Sachs also occurs in a much rarer juvenile or adult form, which occurs in patients in their twenties and early thirties. This is characterized by unsteadiness of gait and progressive neurological deterioration.
The disease was discovered in the family of Rabbi Josef Ekstein in Brooklyn. Four of his children died from it.
Waren Tay in 1881 reported some features of the disease; Bernard Sachs in 1887 presented the first comprehensive description.
- W. Tay:
Symmetrical changes in the region of the yellow spot in each eye of an infant.
Transactions of the Ophthalmological Societies of the United Kingdom, 1881-1882, 1: 55.
- B. Sachs:
On arrested cerebral development, with special reference to its cortical pathology.
Journal of Nervous and Mental Disease, Chicago, 1887; 14: 541-553.
Two further papers on the subject in:
Journal of Nervous and Mental Diseases, Chicago, 1892, 17: 603-607.
Journal of Nervous and Mental Diseases, Chicago, 1896, 21: 475-479.
- Amaurotic family idiocy (Tay-Sachs disease).
In: Modern Medicine: Its Theory and Practice, in Original Contributions by American and Foreign Authors, edited by William Osler, assisted by Thomas McCrae. Philadelphia and New York: Lea & Febiger, 7 volumes, 1907-1910. Volume 7, chapter XXI, pp. 868-874.
- D. G. Cogan:
Amaurotic familial idiocy. A case for eponyms.
New England Journal of Medicine, Boston, 1958, 258: 1212-1213.