GM2A and Tay-Sachs disease: GM2 gangliosidoses including Tay-Sachs disease (TSD, MIM 272800), Sandhoff disease (SD, MIM 268800), and GM2 activator protein deficiency (GM2AP or AB variant, MIM 272750) are a group of lysosomal storage disorders of which the breakdown of glycosphingolipids, GM2 gangliosides, is impaired, leading to an accumulation of the substrates in various internal organs, particular in neuronal cells [1].