Progressive cerebellar ataxia, spasticity, psychomotor retardation, and hexosaminidase deficiency in a 10-year-old child: juvenile Sandhoff disease.

During the course of investigating a 10-year-old boy because of progressive deterioration of intellectual functioning, ataxia, and hemiplegia, an absence of serum hexosaminidase activity was noted. A skin biopsy examined by electron microscopy showed axonal accumulations of dense osmiophilic deposits. Because of the patient's age at onset and the slowly progressive nature of his ilness, we are reporting an atypical juvenile case of Sandhoff disease.