Tay-Sachs isease (abbreviated TSD, also known as GM2 gangliosidosis, Hexosaminidase A deficiency or Sphingolipidosis) is a genetic disorder, fatal in its most common variant known as Infantile Tay-Sachs disease. TSD 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 Tay-Sachs disease, is especially common in the nervous tissue of the brain.