Tay–Sachs disease (also known as
GM2 gangliosidosis or
hexosaminidase A deficiency) is a rare
autosomal recessive genetic disorder. In its most common variant (known as infantile Tay–Sachs disease), it causes a progressive deterioration of
nerve cells and of mental and physical abilities that begins around 7 months of age and usually results in death by the age of four. The disease occurs when harmful quantities of
cell membrane components known as
gangliosides accumulate in the
brain's nerve cells, eventually leading to the premature death of the cells. A ganglioside is a form of
sphingolipid, which makes Tay–Sachs disease a member of the
sphingolipidoses. There is no known cure or treatment.