[Activators for sphingohydrolases and the nature of the sphingomyelinase deficiency in Niemann-Pick disease types A, B and C (author's transl)].

Sphingomyelinase activities have been assayed either in the presence of detergents or by an activator method, in control subjects and patients with Niemann-Pick disease types A, B and C. The activity of this enzyme assayed with detergents compared with that for control subjects is markedly reduced in Niemann-Pick disease types A or B but not in type C. With the activator method, the enzymic activity is strongly reduced in patients with type C (30%) of the control data). This paper describes a reasonably satisfactory method for enzymic diagnosis of Niemann-Pick disease type C. Hypotheses for enzymic mutations in these three types of Niemann-Pick disease are put forward.