<unk>  (abbreviated<unk> , also known as GM2 gangliosidosis, Hexosaminidase A deficiency or Sphingolipidosis) is a genetic disorder, fatal in its most common variant known as Infantile<unk> . <unk>  is inherited in an autosomal recessive pattern. The disease occurs when harmful quantities of a fatty acid derivative called a ganglioside accumulate in the nerve cells of the brain. Gangliosides are lipids, components of cellular membranes, and the ganglioside GM2, implicated in<unk> , is especially common in the nervous tissue of the brain.
The disease is named after the British ophthalmologist Warren<unk>  who first described the red spot on the retina of the eye in 1881, and the American neurologist Bernard<unk>  who described the cellular changes of<unk><unk>  and noted an increased prevalence in the Eastern European Jewish (Ashkenazi) population in 1887.
Research in the late 20th century demonstrated that<unk>  is caused by mutations 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 several populations. French Canadians of southeastern Quebec have a carrier frequency similar to Ashkenazi Jews, but they carry a different mutation. Many Cajuns of southern Louisiana carry the same mutation that is most common in Ashkenazi Jews. Most HEXA mutations are rare, and do not occur in genetically isolated populations. The disease can potentially occur from the inheritance of two unrelated mutations in the HEXA gene, one from each parent.<unk>  is a rare disease. Other autosomal disorders such as cystic fibrosis and sickle cell anemia are far more common. The importance of<unk><unk>  lies in the fact that an inexpensive enzyme assay test was discovered and subsequently automated, providing one of the first "mass screening" tools in medical genetics. In this way, it became a research and public health model for understanding and preventing all autosomal genetic disorders.
Tay-Sachs disease
Sneddon-Wilkinson disease
Naxos disease
Fox-Fordyce disease
Cronkhite–Canada disease
Pickardt syndrome
Leigh's disease
Slone's disease