TAY SACHS DISEASE:
Tay-Sachs disease is a rare autosomal recessive disease which causes a gradual impairment of nerve cells and of mental and physical capabilities. The disease occurs when harmful amounts of cell membrane component called as gangliosides accumulate in the nerve cells of brain. People suffering from Tay-Sachs disease do not have a specific enzyme called hexosaminidase A (Hex-A). The deficiency of this enzyme causes a fat, GM2 ganglioside, to accumulate in the brain. It is this accumulation that causes the symptoms of Tay-Sachs.
This disorder is named after the British scientist, Waren Tay, who first described a symptomatic red mark on the retina of the eye in 1881; and the American neurologist Bernard Sachs, who reported the cellular changes of Tay–Sachs disease in 1887 and observed an increased prevalence of disease in Ashkenazi Jews.
OTHER NAMES:
The Tay Sachs disease is also known by other names like:
B variant GM2 gangliosidosis.
GM2 gangliosidosis, type 1.
Hexosaminidase A deficiency.
Hexosaminidase alpha-subunit deficiency (variant B).
Hex-A deficiency.
Sphingolipidosis, Tay-Sachs.
TSD.
CAUSE OF TAY SACHS DISEASE:
Every individual has two copies of the Tay-Sachs gene (HEXA). Tay-Sachs occurs when both of the HEXA genes are not working in a proper manner because of a mutation. If an individual has one
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This phenomenon is called dominance. Enzymes are catalysts for chemical reactions that increase the rate of reaction without being used up in the process, so only small amounts of enzyme are required to carry out a reaction. A homozygous individual for a nonfunctional mutation in the enzyme-encoding gene has no enzyme activity, so it will show the abnormal phenotype. A heterozygote has at least half of the normal enzyme activity level. This level is normally sufficient for normal function and thus prevents phenotypic