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Sandhoff disease is a lysosomal storage disorder from the GM2 gangliosidosis family and is characterised by central nervous system degeneration. Prevalence in Europe is about 1/130 000. The clinical picture is identical to that of Tay-Sachs disease, with startle reactions, early blindness, progressive motor and mental deterioration, macrocephaly and cherry-red spots on the macula. Patients may have a doll-like face, hepatosplenomegaly and recurring respiratory tract infections. High levels of urinary oligosaccharides are found. Children develop normally during the first 3-6 months of life, after which the disease appears and evolves quickly. In cases with later onset, or in adult cases, signs may be those of spinocerebellous ataxia or dystonia. Intellectual capacities may or may not be affected. The condition is an autosomal recessive inherited trait. It results from hexosaminidase A and B deficiency, linked to an abnormal beta subunit (while Tay-Sachs disease results from hexosaminidase A deficiency caused by an abnormal alpha subunit). This enzymatic defect leads to abnormal GM2 ganglioside storage in neurons and peripheral tissues. The causative gene is located on chromosome 5 (5q13). There is no specific treatment available for this disease, and the prognosis is poor, with death usually occurring by age of 4 years.
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