A Natural History of Late Onset Tay-Sachs Disease

Inclusion Criteria: * The subject must have a confirmed diagnosis of Late Onset GM2 Gangliosidosis as defined by (a) absent to near-absent beta-hexosaminidase enzymatic activity in the serum or white blood cells or (b) mutation analysis of the HEXA and HEXB genes to distinguish pseudo deficiency alleles from disease-causing alleles * The subject must be older than 7 years of age Exclusion Criteria: * If a patient is very severely affected by the disease, the PI will assess whether it is in the best interest of the patient to exclude them from the study for their own comfort and well being. In cases where the PI deems it appropriate, severely affected patients will be excluded. Patients under the age of 7 years will be excluded from this study.