Niemann-Pick Disease Type A and B are Clinically but also Enzymatically Heterogeneous: Pitfall in the Laboratory Diagnosis of Sphingomyelinase Deficiency Associated with the Mutation Q292 K - Harzer, K; Rolfs, A; Bauer, P; Zschiesche, M; Mengel, E; Backes, J; Kustermann-Kuhn, B; Bruchelt, G; van Diggelen, O P; Mayrhofer, H; Krägeloh-Mann, I (Neuropediatrics, 2003)