Niemann-Pick type C disease: NPC1 mutations associated with severe and mild cellular cholesterol trafficking alterations

I. Ribeiro, A. Marcão, O. Amaral, M.C. Sá Miranda: Genetic Neurobiology, IBMC University of Porto,4150-180 Porto, Portugal and Enzymology Unit,Institute of Medical Genetics Jacinto de Magalhães,4050-466 Porto, Portugal M.T. Vanier, G. Millat: INSERM U189, Lyon-Sud Medical School, 69921 Oullins and Fondation Gillet-Mérieux, Lyon-Sud Hospital,69495 Pierre Bénite, FranceNiemann-Pick type C disease (NPC) is a rare neurodegenerative disorder characterised by lysosomal/late endosomal accumulation of endocytosed unesterified cholesterol and delayed induction of cholesterol homeostatic reactions. The large majority of mutations in the NPC1 gene described thus far have been associated with severe cellular cholesterol trafficking impairment (classic biochemical phenotype, present in about 85% of NPC patients). In our population of 13 unrelated NP-C1 patients, among which 12 were of Portuguese extraction, we observed an unusually large proportion of families presenting mild alterations of intracellular cholesterol transport (variant biochemical phenotype), without strict correlation between the biochemical phenotype and the clinical expression of the disease. Mutational studies were carried out to compare molecular lesions associated with severe and mild cholesterol traffic impairment. Levels of NPC1 protein were studied by Western blot in cultured fibroblasts of four patients with homozygous mutant alleles. Ten novel mutations were identified (Q92R, C177Y, R518W, W942C, R978C, A1035V, 2129delA, 3662delT, IVS23+1 G>A and IVS16-82 G>A). The mutational profile appeared to be correlated with the biochemical phenotype. Splicing mutations, I1061T and A1035V, corresponded to "classic" alleles, while three missense mutations, C177Y, R978C and P1007A, could be defined as "variant" alleles. All "variant" mutations described so far appear to be clustered within the cysteine-rich luminal loop between TM 8 and 9, with the remarkable exception of C177Y. The latter mutant allele, at variance with P1007A, was correlated to a decreased level of NPC1 protein and a severe course of the disease, and disclosed a new location for "variant" mutations, the luminal loop located at the N-terminal end of the protein.FCT (Portugal) PRAXISXX1/BD/16058/ and Vaincre les Maladies Lysosomales and INSERM U189. G. Millat was the recipient of a fellowship from Vaincre les Maladies Lysosomales

Identification of HE1 as the second gene of Niemann-Pick C disease

Niemann-Pick type C2 disease (NP-C2) is a fatal hereditary disorder of unknown etiology characterized by defective egress of cholesterol from lysosomes. Here we show that the disease is caused by a deficiency in HE1, a ubiquitously expressed lysosomal protein identified previously as a cholesterol-binding protein. HE1 was undetectable in fibroblasts from NP-C2 patients but present in fibroblasts from unaffected controls and NP-C1 patients. Mutations in the HE1 gene, which maps to chromosome 14q24.3, were found in NP-C2 patients but not in controls. Treatment of NP-C2 fibroblasts with exogenous recombinant HE1 protein ameliorated lysosomal accumulation of low density lipoprotein–derived cholesterol. </jats:p

Niemann-Pick type C disease: A novel NPC1 mutation segregating in a Greek island

Niemann-Pick type C (NPC) disease is a rare autosomal recessive lysosomal storage disease, exhibiting an extremely heterogeneous clinical phenotype. It is a cellular lipid trafficking disorder characterized by the accumulation in the lysosomal/late endosomal system of a variety of lipids, especially unesterified cholesterol. So far two genes, NPC1 or NPC2, have been linked to the disorder. It is a panethnic disease for which two isolates have been described. We present a novel NPC1 mutation (p.A1132P; c.3394G&gt;C) identified in homozygosity in two patients originating from the same small town of an Aegean Sea island and the results of the broad screening of their extended families. Overall 153 individuals have so far been investigated and a total of 64 carriers were identified. Moreover a common descent of the individuals tested was revealed and all carriers could be traced back to a common surname, apparently originating from a common ancestor couple six generations back. The mutation was found associated with an uncommon haplotype in the island that is also present in other populations. © 2013 John Wiley &amp; Sons A/S

The spectrum of niemann-pick type C disease in greece

Niemann-Pick type C disease (NPC) is a neurovisceral lysosomal storage disease caused by mutations in either the NPC1 or the NPC2 gene. It is a cellular lipid trafficking disorder characterized by the accumulation of unesterified cholesterol and various sphingolipids in the lysosomes and late endosomes, and it exhibits a broad clinical spectrum. Today, over 420 disease-causing mutations have been identified in the NPC1 and the NPC2 genes. We present the clinical, biochemical, and molecular findings in 14 cases diagnosed in Greece during the last 28 years. Age at diagnosis ranged from 2.5 months to 48 years. Systemic manifestations were present in 7/14 patients. All developed neurological manifestations (age of onset 5 months to 42 years). Six patients are still alive (age: 5–50 years). Classical filipin staining pattern was observed in all but four patients (3 NPC1, 1 NPC2). The rate of LDL-induced cholesteryl ester formation was severely reduced in 4/7 and significantly reduced in 3/7 patients studied. Increased chitotriosidase activity was observed in 9/12 patients. Mutation analysis in 11 unrelated patients identified 12 different mutations in the NPC1 gene: eight previously described p.E1089K (c.3265G&gt;A), p.F284Lfs*26 (c.852delT), p.A1132P(c.3394G&gt;C), del promoter region and exons 1-10, p.R1186H (c.3557G&gt;A), p.P1007A (c.3019C&gt;G), p.Q92R(c.275A&gt;G),p.S940L (c.2819C&gt;T), and four novel ones: (p.N701K fs*13 (c.2102-2103insA), p.K1057R (c.3170A&gt;G), IVS23+3insT(c.3591+3insT), p.C1119*(c.3357T&gt;C); and the previously described IVS2+5G&gt;A(c.190+5G&gt;A) mutation in the NPC2 gene. All patients were of Greek origin. Assuming a birth rate of 100,000/year, a rough incidence estimate for NPC disease in Greece would be 0.5/100,000 births. © SSIEM and Springer-Verlag Berlin Heidelberg 2017

Niemann-Pick disease type B: An unusual clinical presentation with multiple vertebral fractures

We report here a unique case of a 55-year-old woman presenting with a clinical picture of Parkinson disease, severe back pain, splenomegaly, and pronounced dyspnea. Radiographic examination of the spine showed multiple vertebral fractures. Niemann-Pick disease type B was diagnosed by findings of lipid-loaded histiocytes and a strongly reduced sphingomyelinase enzyme activity. She was homozygous for the deletion of codon 608 (delR608), which encodes an arginine residue in the Acid Sphingomyelinase gene. To investigate the cause of the unusual vertebral fractures, we screened for polymorphisms previously described as possibly associated with increased risk for osteoporosis and fractures. Our patient was heterozygous for the polymorphisms of the vitamin D receptor gene, the estrogen receptor gene, and the collagen 1A1gene. Increased physical activity after Parkinson treatment, a genetic predisposition, together with worsening disease due to interfering medications could explain the dramatic presentation of this patient. She was treated with cholesterol lowering drugs such as statins to decrease sphingomyelin synthesis, avoidance of drugs that inhibit sphingomyelinase, and bisphosphonates. No new fractures have occurred, but the interstitial lung disease has progressed