There are two forms of gangliodosis. GM1 gangliodsidosis affects the enzyme á-galactosidase and produces storage of GM1 ganliosides; the affected chromosome is number 3. GM2 gangliosidosis, AB variant affects the production of the GM2 activator protein enzyme and causes the storage of GM2 ganglioside; the affected chromosome is 5. Tay-Sachs disease is often called GM2 gangliosidosis, Type I; Sandhoff disease GM2 gangliosidosis Type 2.