The cherry red spot-myoclonus syndrome: a newly recognized inherited lysosomal storage disease due to acid neuraminidase deficiency.

A newly discovered lysosomal storage disorder, apparently transmitted as an autosomal recessive trait, presents with cherry red spots in childhood, progressive debilitating myoclonus, insidious visual loss, and normal intelligence. Somatic and bony abnormalities are not evident clinically. Neuronal lipidosis and vacuolated Kuppfer cells are found upon tissue examination. The diagnosis can be most easily confirmed by chromatographic screening for urinary sialyloligosaccharides. The primary enzyme defect is a deficiency of an acid neuraminidase isoenzyme which cleaves sialyloligosaccharides. I discuss here the clinical phenotype in four patients, the chemical abnormality, the pathogenesis, the enzyme defect and the molecular genetics of this disorder.