[Early infantile form of Niemann-Pick disease type C. Apropos of 2 siblings].

We report two cases of Niemann-Pick disease in a sister and brother. Early jaundice was the first manifestation in both cases and was followed by cachexia and a rapidly fatal outcome. Neurologic involvement was obvious in both patients. Biologic phenotype was consistent with a diagnosis of type C sphingomyelinase, although clinical expression was different. These two cases should be classified within the infantile and early forms of Niemann-Pick disease type C. Antenatal diagnosis was performed during a third pregnancy. Enzyme activity assays on a specimen of trophoblast taken at the tenth week of gestation showed the fetus was not affected. This diagnosis was confirmed by a normal clinical evaluation at two months of life, and normal sphingomyelinase activity of cultured skin fibroblasts.