Tay–Sachs disease

Tay–Sachs disease is an inherited lysosomal storage disorder caused by deficient hexosaminidase A. GM2 ganglioside accumulates in nerve cells, causing progressive neurological damage.

Hexosaminidase A: A lysosomal enzyme that breaks down GM2 ganglioside and other molecules. Its deficient activity is the biochemical defect at the center of Tay–Sachs disease.
Autosomal recessive inheritance: A pattern in which a condition usually occurs when both copies of a gene carry disease-causing variants. Tay–Sachs disease typically develops when a person inherits pathogenic HEXA variants from both parents.
Newborn screening: Testing performed soon after birth to identify conditions before symptoms appear. Screening programs can identify Tay–Sachs in some regions, enabling early follow-up.
Sandhoff disease: An inherited GM2 gangliosidosis caused by deficiency of both hexosaminidase A and B. It also causes GM2 accumulation, but results from variants in HEXB rather than HEXA.
Infantile Tay–Sachs disease: The classic early-onset form of Tay–Sachs disease, usually beginning in infancy with progressive neurological decline. This severe form is the best-known clinical presentation of the disease.
HEXA: A gene encoding the alpha subunit of lysosomal hexosaminidase A. Pathogenic variants in HEXA commonly prevent production of functional enzyme.
Lysosomal storage disease: A group of inherited disorders caused by defects in lysosomal breakdown or transport. Tay–Sachs belongs to this group because undegraded material builds up inside cells.
Carrier screening: Genetic testing used to determine whether someone carries a variant associated with a recessive condition. HEXA carrier testing informs reproductive decisions and has reduced disease incidence in some populations.
GM2 gangliosidosis: A group of inherited disorders in which GM2 ganglioside accumulates because its degradation is impaired. Tay–Sachs is one form of this disease group, alongside Sandhoff disease and related conditions.
Ashkenazi Jews: A Jewish diaspora population with historical roots in Central and Eastern Europe. Some HEXA variants are more frequent in this population, prompting targeted carrier-screening programs.

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