HEXB and Sandhoff disease: Sandhoff disease (0.25 in 100,000; Meikle et al., 1999) results from LoF mutations in the HEXB gene on chromosome 5, critical for the lysosomal enzymes beta-N-acetylhexosaminidase A and B. The GM2 AB variant is caused by gene mutations causing cofactor GM2 activator deficiency leading to lack of the normal beta-hexosaminidase A. With no authorized treatments available the current standard of care for GM2 gangliosidosis is limited to supportive care aimed at providing adequate nutrition and hydration.