Sandhoff disease is an inherited disorder caused by defective enzymes, beta-hexosaminidase A and B, that help to break down fatty substances and sugar molecules within the cell. These compounds start to accumulate to toxic levels, particularly in cells in the brain and spinal cord. This eventually leads to the destruction of these cells. In the most common form of Sandhoff disease, symptoms start in infancy. Infants are normal for the first few months and then their development slows and their muscles weaken. They lose all motor skills and startle easily. As the disease progresses, they will have seizures, vision and hearing loss, intellectual disability, and paralysis. Eye examinations in these patients will identify a cherry-red spot that is characteristic to this disorder. Children with this severe form die in early childhood. There are later onset forms of Sandhoff disease that occur less commonly. Onset starts in childhood on into adulthood and symptoms are milder.These individuals may have muscle weakness, loss of coordination, mild intellectual disability, and mental illness. There is no cure for Sandhoff disease but medical surveillance and care may help to improve some symptoms and overall condition of life. Sandhoff disease is caused by pathogenic variants in the HEXB gene.