TY - JOUR
T1 - Identification and characterization of eight novel SMPD1 mutations causing types A and B Niemann-Pick disease
AU - Desnick, Jonathan P.
AU - Kim, Jungmin
AU - He, Xingxuan
AU - Wasserstein, Melissa P.
AU - Simonaro, Calogera M.
AU - Schuchman, Edward H.
N1 - Copyright:
Copyright 2015 Elsevier B.V., All rights reserved.
PY - 2010
Y1 - 2010
N2 - Types A and B Niemann-Pick disease (NPD) result from the deficient activity of acid sphingomyelinase (ASM), due to mutations in the sphingomyelin phosphodiesterase 1 (SMPD1) gene. Here we report the identification, characterization and genotype/phenotype correlations of eight novel mutations in six unrelated NPD patients. These mutations included seven missense mutations: c.631T > C (p.W211R), c.757G > C (p.D253H), c.940G > A (p.V314M), c.1280A > G (p.H427R), c.1564A > G (p.N522S), c.1575G > C (p.Q525H) and c.1729A > G (p.H577R), and a novel frameshift mutation, c.1657delACCGCCT (fsT553). Each missense mutation was expressed in 293T or COS-7 cells; mutant enzymes p.W211R, p.D253H, p.H427R and p.H577R had <1% of expressed wild-type activity, whereas p.V314M, p.N522S and p.Q525H had 21.7%, 10.1% and 64% of expressed wild-type activity, respectively. The c.1564A > G mutation obliterated a known N-glycosylation site and its p.N522S mutant enzyme had ~10% of expressed wild-type activity. Western blot analysis revealed that each mutant protein was expressed at near wild-type amounts, despite their differences in residual activity. The novel seven-base deletion occurred at codon 553, leading to a premature truncation after residue 609. The expression studies predicted the clinical phenotypes of the six patients: two type A patients had genotypes with only type A alleles [c.631T > C (p.W211R), c.757G > C (p.D253H) and c.1729A > G (p.H577R)], and the other four type B disease patients had at least one neuroprotective mutant type B allele [c.940G > A (p.V314M), c.1280A > G (p.H427R), c.1564A > G (p.N522S) and c.1575G > C (p.Q525H)] that expressed >5% residual ASM activity. Thus, these new mutations provide novel genotype/phenotype correlations and further document the genetic heterogeneity in types A and B NPD.
AB - Types A and B Niemann-Pick disease (NPD) result from the deficient activity of acid sphingomyelinase (ASM), due to mutations in the sphingomyelin phosphodiesterase 1 (SMPD1) gene. Here we report the identification, characterization and genotype/phenotype correlations of eight novel mutations in six unrelated NPD patients. These mutations included seven missense mutations: c.631T > C (p.W211R), c.757G > C (p.D253H), c.940G > A (p.V314M), c.1280A > G (p.H427R), c.1564A > G (p.N522S), c.1575G > C (p.Q525H) and c.1729A > G (p.H577R), and a novel frameshift mutation, c.1657delACCGCCT (fsT553). Each missense mutation was expressed in 293T or COS-7 cells; mutant enzymes p.W211R, p.D253H, p.H427R and p.H577R had <1% of expressed wild-type activity, whereas p.V314M, p.N522S and p.Q525H had 21.7%, 10.1% and 64% of expressed wild-type activity, respectively. The c.1564A > G mutation obliterated a known N-glycosylation site and its p.N522S mutant enzyme had ~10% of expressed wild-type activity. Western blot analysis revealed that each mutant protein was expressed at near wild-type amounts, despite their differences in residual activity. The novel seven-base deletion occurred at codon 553, leading to a premature truncation after residue 609. The expression studies predicted the clinical phenotypes of the six patients: two type A patients had genotypes with only type A alleles [c.631T > C (p.W211R), c.757G > C (p.D253H) and c.1729A > G (p.H577R)], and the other four type B disease patients had at least one neuroprotective mutant type B allele [c.940G > A (p.V314M), c.1280A > G (p.H427R), c.1564A > G (p.N522S) and c.1575G > C (p.Q525H)] that expressed >5% residual ASM activity. Thus, these new mutations provide novel genotype/phenotype correlations and further document the genetic heterogeneity in types A and B NPD.
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U2 - 10.2119/molmed.2010.00017
DO - 10.2119/molmed.2010.00017
M3 - Article
C2 - 20386867
AN - SCOPUS:77954279039
VL - 16
SP - 316
EP - 321
JO - Molecular Medicine
JF - Molecular Medicine
SN - 1076-1551
IS - 7-8
ER -