[Niemann-Pick disease type C (subacute neurovisceral lipidosis). Problems of altered sphingomyelinase activity in the brain (author's transl)].

One fetus (20 weeks old) and two postnatal cases with Niemann-Pick disease type C (a group of unclear neurovisceral lipidoses characterized by foam cells in the bone marrow and sometimes supranuclear ophthalmoplegia) were studied with respect to the pH-dependency of brain sphingomyelinase activity. A distinct reduction of activity in the pH 5 range of the fetus was contrary to an almost normal pH profile in the postnatal cases including the sibling of the fetus. The sphingomyelinase anomaly does not seem to reflect the genetic defect, since it is paralleled by a similar anomaly of glucocerebrosidase activity. A pathologic subcellular localization of more than one lipid hydrolasis is discussed.