The three known types of GM2 gangliosidosis are Tay-Sachs Disease (TSD), Sandhoff Disease (SD), and AB-variant GM2 gangliosidosis (ABGM2), which manifest through a partial or complete loss-of-function mutation in genes encoding β-N-acetylhexosaminidase A (β-HexA) or GM2 activator (GM2A) proteins, both required for GM2 catabolism. This evidence concerns the gene GM2A and GM2 gangliosidosis.