HEXB and Sandhoff disease: Inherited mutations in glycosidase genes are the origins of several human lysosomal storage diseases including sialidosis due to deficiency of neuraminidase NEU1 (3, 4), GM1 gangliosidosis and Morquio B disease due to deficiency of β-galactosidase GLB1 (5, 6), Sandhoff disease/GM2 gangliosidosis due to deficiency of β-N-acetylglucosaminidase HEXB (7), mannosidosis due to deficiency of α-mannosidase MAN2B1 (8, 9), and fucosidosis due to deficiency of tissue α-L-fucosidase FUCA1 (10).