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

摘要: This study describes a diagnostic pitfall in the laboratory diagnosis of patients with sphingomyelinase deficiency (SMD; Niemann-Pick disease types A and B; NPA NPB), cases where activity was not determined sphingomyelin as natural enzymic substrate. Four 24 SMD studied had falsely normal or enhanced activity, when so-called artificial substrate, 2-N-(hexadecanoyl)-amino-4-nitrophenyl phosphorylcholine (HNP), used, whereas clear Those four Q292 K mutation acid gene (SMPD1) on at least one allele. Three (no data available from one) experienced only late-infantile juvenile, though distinct, neurological involvement, learning disabilities, hypo- areflexia mild ataxia were initial signs. The HNP which is used many laboratories, raises risk that some are overlooked, it prevents consideration late-manifesting course well planning enzyme substitution therapy non-neurological (NPB) patients. Since classical NPB very rare, suggested late- mild-manifesting symptoms should better be assigned to additional subgroups than grouped NPB.