Clinical heterogeneity in a sibship with Niemann-Pick disease type C.

The clinical presentation of Niemann-Pick type C is variable. However, in families hitherto described, the affected individuals in a given sibship show a similar clinical course. A family with histological and biochemical findings of Niemann-Pick type C is described. Four of the affected siblings presented with an early onset and a fulminant course resembling Niemann-Pick type A, whereas in the fifth sibling a later onset and a much slower neurological deterioration was observed. Genetic counseling in families with Niemann-Pick type C should take into consideration the possibility of clinical heterogeneity within the same sibship.