Also Known As: Tay-Sachs disease, TSD, GM2 ganliodisosis
Tayâ€“Sachs disease (abbreviated TSD, also known as GM2 gangliosidosis or Hexosaminidase A deficiency) is an autosomal recessive genetic disorder. In its most common variant, known as infantile Tayâ€“Sachs disease, it causes a relentless deterioration of mental and physical abilities that commences around six months of age and usually results in death by the age of four. It is caused by a genetic defect in a single gene with one defective copy of that gene inherited from each parent. The disease occurs when harmful quantities of cell membrane components known as gangliosides accumulate in the nerve cells of the brain, eventually leading to the premature death of those cells. There is no cure or treatment.
The disease is named after British ophthalmologist Warren Tay, who first described the red spot on the retina of the eye in 1881, and the American neurologist Bernard Sachs of Mount Sinai Hospital, New York who described the cellular changes of Tayâ€“Sachs and noted an increased prevalence in the Eastern European Ashkenazi Jewish population in 1887.
Research in the late 20th century demonstrated that Tayâ€“Sachs disease is caused by a genetic mutation on the HEXA gene on chromosome 15. A large number of HEXA mutations have been discovered, and new ones are still being reported. These mutations reach significant frequencies in populations. French Canadians of southeastern Quebec have a carrier frequency similar to Ashkenazi Jews, but they carry a different mutation. Cajuns of southern Louisiana carry the same mutation that is most common in Ashkenazi Jews. HEXA mutations are rare, and do not occur in genetically isolated populations. The disease can occur from the inheritance of two unrelated mutations in the HEXA gene.