Tay-Sachs Disease is a progressive and fatal genetic condition that involves a complete deficiency of the hexosaminidase-A (HEXA) enzyme. This enzyme is needed in healthy individuals for the process of hydrolysis of GM2 ganglioside to occur. For individuals with Tay-Sachs disease that lack this enzyme, the fatty substance of GM2 ganglioside accumulates in the brain and leads to the symptoms of the disease.
Tay-Sachs, an inherited neurological disorder, is unusually common among French Canadians from eastern Quebec. Two alleles are responsible, one being specific to the north shore of the St. Lawrence and the other to the south shore. This pattern of convergent evolution suggests the presence of a selection pressure limited to eastern Quebec. Both alleles probably arose after the British conquest of Quebec in 1759 or at least were uncommon previously.
There's currently no cure for Tay-Sachs disease, so the aim of treatment is to make living with the condition as comfortable as possible. Treatment usually focuses on the Preventing problems with the lungs and airways, relieving any feeding or swallowing problems (dysphagia) and using medication to help control or relieve symptoms, such as fits and muscle stiffness.