Tay-Sachs disease

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Tay-Sachs disease

Tay-Sachs disease (tāˈ-săksˈ), rare hereditary disease caused by a genetic mutation that leaves the body unable to produce an enzyme necessary for fat metabolism in nerve cells, producing central nervous system degeneration. The disease is named for a British ophthalmologist, Warren Tay, who first described the disease, in 1881, and a New York neurologist, Bernard Sachs, who first described the cellular changes and the genetic nature of the disease, in 1887. In infants, it is characterized by progressive mental deterioration, blindness, paralysis, epileptic seizures, and death, usually between ages three and five. Late-onset Tay-Sachs occurs in persons who have a genetic mutation that is similar but allows some production of the missing enzyme. There is no treatment for Tay-Sachs.

Course of the Disease

The enzyme involved in Tay-Sachs is called hexosaminidase A. Its absence allows a lipid called GM2 ganglioside to build up in the brain, destroying the nerve cells. The process starts in the fetus; the disease is clinically apparent in the first few months of life. Initial symptoms vary, but usually include a general slowing of development and loss of peripheral vision. By the age of one, most children are experiencing convulsions. The damage to the nervous system progresses inexorably, bringing with it an inability to swallow, difficulty in breathing, blindness, mental retardation, and paralysis.

In late-onset Tay-Sachs, which is often misdiagnosed, the symptoms (ataxia, dysarthria, and muscle weakness) usually become apparent late in childhood or early in adulthood. About 40% of the patients display symptoms of bipolar disorder. Life expectancy does not appear to be affected.

Genetic Basis and Screening

Tay-Sachs disease occurs primarily among Jews of Eastern European descent but is also found in French Canadians whose roots are in the St. Lawrence region, certain Cajuns in Louisiana, and some Amish communities. Tay-Sachs is an autosomal recessive disorder; a person must have two defective genes (one from each parent) in order for the disease to occur. Carriers, people with only one gene for the disorder, are physically unaffected. When both parents are carriers, each child has a 25% chance of getting the disease. If only one parent is a carrier, there is no chance that the child will get the disease, but there is a 50% chance that the child will be a carrier. The gene may be carried by many generations without a manifestation. For this reason, plus the historical lack of accurate diagnosis and routinely high infant mortality of past generations, there is often no known family history of the disease.

Genetic screening (see genetic testing) for the disease has been possible since the early 1970s and is encouraged in high-risk populations. Blood tests of carriers reveal a reduced amount of the hexosaminidase A. If a couple elects to go forward with a pregnancy, fetal status (again utilizing hexosaminidase A levels) can be ascertained via chorionic villus sampling or amniocentesis. Genetic screening and counseling has greatly reduced the incidence of the disease.


See M. M. Kaback, ed., Tay-Sachs Disease: Screening and Prevention (1977); W. Stockton, Altered Destinies (1979).

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Tay-Sachs disease

[¦tā ¦saks di‚zēz]
A form of sphingolipidosis, transmitted as an autosomal recessive, in which there is an accumulation in neuronal cells of the neuraminic fraction of gangliosides; manifested clinically within the first few months of life by hypotonia progressing to spasticity, convulsions, and visual loss accompanied by the appearance of a cherry-red spot at the macula lutea. Also known as infantile amaurotic familial idiocy.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
1930 "Amaurotic family idiocy (Tay-Sachs disease) clinical report of a case." Journal of Nervous and Mental Disease 71: 268-70.
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See also: Ataxia, Neurometabolic Disorders, Tay-Sachs Disease
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Screening during pregnancy to determine if one or both parents are carriers of genetic disorders historically has involved testing for a limited number of conditions, such as cystic fibrosis, hemoglobinopathies, and Tay-Sachs disease. Patients usually are offered testing for 1 or 2 disorders, with test choices primarily based on patient race and ethnicity.
GM2 gangliosidoses including Tay-Sachs disease [TSD, Online Mendelian Inheritance in Man (OMIM) 272800], Sandhoff disease (SD, OMIM 268800) and GM2 activator protein deficiency (GM2; OMIM 272750) are rare lysosomal storage disorders of the sphingolipid metabolism due to an autosomal recessive inheritance.
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Kaplan, "Tay-Sachs disease screening and diagnosis: evolving technologies," DNA and Cell Biology, vol.
Ashkenazi Jews, for example, are most likely to be carriers of the mutated HEXA gene linked to (http://www.nhs.uk/Conditions/Tay-Sachs-disease/Pages/Introduction.aspx) Tay-Sachs disease , a fatal genetic disorder.
Non-invasive prenatal testing (NIPT) test can detect birth defects such as neural tube defects, Down syndrome, chromosome abnormalities, genetic disorders and other conditions, such as spina bifida, cleft palate, Tay-Sachs disease, sickle cell anemia, thalassemia, cystic fibrosis, Muscular dystrophy, and fragile X syndrome.
It is not about questioning God's purposes in the context of Tay-Sachs Disease, as the title might suggest.