The GM2 gangliosidoses are rare autosomal recessive genetic disorders that include Tay-Sachs disease (TSD, OMIM 272800), Sandhoff disease (SD, OMIM 268800) and GM2 ganglioside activator protein (GM2A) deficiency (variant AB, OMIM 272750) [31]. Here, GM2A is linked to Sandhoff disease.