[Type C Niemann-Pick disease in 2 siblings. Biochemical bases of its diagnosis]

Two brothers, a seven-year-old male and a nine-year-old female are reported. Clinical features include scholar troubles and clumsiness, hepatosplenomegaly, vertical supranuclear ophthalmoplegia and ataxic gait. Moreover, the girl showed intention tremor. Foamy histiocytes were seen in bone marrow and some Niemann-Pick type Kupffer cells were present in liver. Girl's conjunctival biopsy showed lamellar inclusions. Biochemical studies were performed in girl's skin and liver biopsies. Sphingomyelinase activity assayed with 14C sphingomieline in cultured skin fibroblasts was 26% at the mean control value. Liver lipid composition did not show an appreciable increase of sphingomyelin or cholesterol, but bis (monoacylglyceryl) phosphate was clearly elevated. These data are compatible with Niemann-Pick disease type C.