This study describes a diagnostic pitfall in the laboratory diagnosis of patients with sphingomyelinase deficiency (SMD; Niemann-Pick disease types A and B; NPA and NPB), in cases where sphingomyelinase activity was not determined with sphingomyelin as the natural enzymic substrate.
The intracellular proteins cathepsin B and L, two-pore channel 1 and 2, and bona fide receptor Niemann⁻Pick Disease C1 (NPC1) are essential for the endosomal phase of cell entry.
The Niemann-Pick disease group is now divided into two distinct entities: (1) acid sphingomyelinase-deficient Niemann-Pick disease (ASM-deficient NPD) resulting from mutations in the SMPD1 gene and encompassing type A and type B as well as intermediate forms; (2) Niemann-Pick disease type C (NP-C) including also type D, resulting from mutations in either the NPC1 or the NPC2 gene.
Comprehensive Evaluation of Plasma 7-Ketocholesterol and Cholestan-3β,5α,6β-Triol in an Italian Cohort of Patients Affected by Niemann-Pick Disease due to NPC1 and SMPD1 Mutations.
The Niemann-Pick disease group is now divided into two distinct entities: (1) acid sphingomyelinase-deficient Niemann-Pick disease (ASM-deficient NPD) resulting from mutations in the SMPD1 gene and encompassing type A and type B as well as intermediate forms; (2) Niemann-Pick disease type C (NP-C) including also type D, resulting from mutations in either the NPC1 or the NPC2 gene.
It also accumulates in Niemann-Pick disease types A and B with primary storage of SM and with cholesterol in type C. Reconstitution of GM2 catabolism with β-hexosaminidase A and GM2 activator protein (GM2AP) at uncharged liposomal surfaces carrying GM2 as substrate generated only a physiologically irrelevant catabolic rate, even at pH 4.2.
To test whether reduction in lysosomal enzymatic activity in PD is specific to GCase, we measured GCase, acid sphingomyelinase (deficient in Niemann-Pick disease types A and B), alpha galactosidase A (deficient in Fabry), acid alpha-glucosidase (deficient in Pompe) and galactosylceramidase (deficient in Krabbe) enzymatic activities in dried blood spots of PD patients (n = 648) and controls (n = 317) recruited from Columbia University.
Type B NPD cells were transduced with retroviral vectors expressing ASM, labeled with lissamine rhodamine sphingomyelin (LR-SPM), and subjected to preparative fluorescence-activated cell sorting (FACS).
Genetic alterations in ASM lead to ASM deficiency (ASMD) and have been linked to Niemann-Pick disease types A and B. Olipudase alfa, a recombinant form of human ASM, is being developed as enzyme replacement therapy to treat the non-neurological manifestations of ASMD.
Niemann-Pick disease (NPD) is a hereditary lysosomal storage disorder in which mutations in the sphingomyelin phosphodiesterase gene leads to partial or complete deficiency of the sphingomyelinase enzyme.
In addition to its role in NPD, over the past two decades, the importance of sphingolipids, and ASM in particular, in normal physiology and the pathophysiology of numerous common diseases also has become known.
ASM deficient lymphoblasts derived from patients with Niemann-Pick disease (NPD) fail to undergo apoptosis in response to external signals and Fas cross-linking.
Acid sphingomyelinase deficiency. Phenotype variability with prevalence of intermediate phenotype in a series of twenty-five Czech and Slovak patients. A multi-approach study.
These data thus demonstrate, for the first time, imprinting at the SMPD1 gene and reveal the influence of this epigenetic modification on the presentation of ASM-deficient NPD.
Fluorescence-based selection of gene-corrected hematopoietic stem and progenitor cells from acid sphingomyelinase-deficient mice: implications for Niemann-Pick disease gene therapy and the development of improved stem cell gene transfer procedures.
To evaluate the feasibility of somatic gene therapy for the treatment of these disorders, retroviral-mediated gene transfer was used to introduce the full-length ASM cDNA into cultured fibroblasts from two unrelated type A NPD patients.