Early diagnosis in Niemann-Pick disease.

Hepatosplenomegaly, observed on routine physical examination of a 3-month-old French-Canadian infant, was the first evidence for the possibility of Niemann-Pick disease. Vacuolated foam cells filled with phospholipid material were found in liver and bone marrow biopsy material. The absence of sphingomyelinase activity in isolated peripheral leukocytes and cultured skin fibroblasts confirmed the diagnosis. The parents' leukocytes displayed significantly less activity than was found in control cells. Exact and early confirmation of the diagnosis of Niemann-Pick disease is of prime importance for it allows the physician to offer a more specific prognosis, to provide more precise genetic counselling for the couple at risk and, finally, to offer the possibility of prenatal diagnosis.