HEXB and Sandhoff disease: Hypomyelination was reported in several LSDs, including GM1 gangliosidosis with deficiency in acid β-galactosidase due to GLB1 mutations, and GM2 gangliosidosis with deficiency in β-hexosaminidase A (Tay-Sachs disease, HEXA mutations) or β-hexosaminidases A and B (Sandhoff disease, HEXB mutations)[6, 38, 63–66].