A lysosomal disorder from the GM2 gangliosidosis family, caused by biallelic pathogenic variants in the HEXB gene, characterized by GM2 ganglioside accumulation in the nervous system and progressive central nervous system degeneration. The disease is Sandhoff disease (MONDO_0010006). Also known as: GM2 gangliosidosis 0 variant, GM2 gangliosidosis, 0 variant, Hexosaminidases A and B deficiency, Sandhoff Jatzkewitz disease.