TY - JOUR
T1 - Niemann-Pick C variant detection by altered sphingolipid trafficking and correlation with mutations within a specific domain of NPC1
AU - Sun, Xiaofeng
AU - Marks, David L.
AU - Park, Walter D.
AU - Wheatley, Christine L.
AU - Puri, Vishwajeet
AU - O’Brien, John F.
AU - Kraft, Daniel L.
AU - Lundquist, Patrick A.
AU - Patterson, Marc C.
AU - Pagano, Richard E.
AU - Snow, Karen
N1 - Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 2001/6
Y1 - 2001/6
N2 - Niemann-Pick disease type C (NPC) is a fatal, autosomal recessive lipidosis characterized by lysosomal accumulation of unesterified cholesterol and multiple neurological symptoms, such as vertical supranuclear ophthalmoplegia, progressive ataxia, and dementia. More than 90% of cases of NPC are due to a defect in Niemann-Pick C1 (NPC1), a late endosomal, integral membrane protein that plays a role in cholesterol transport or homeostasis. Biochemical diagnosis of NPC has relied on the use of patient skin fibroblasts in an assay to demonstrate delayed low-density lipoprotein (LDL)-derived cholesterol esterification and a cytological technique-filipin staining-to demonstrate the intracellular accumulation of cholesterol. A small percentage of patients, referred to as "NPC variants," present with clinical symptoms of NPC but show near-normal results of these biochemical tests, making laboratory confirmation of NPC disease problematic. Here, we demonstrate that NPC-variant fibroblast samples can be detected as sphingolipid storage disease cells, using a fluorescent sphingolipid analog, BODIPY-lactosylceramide. This lipid accumulated in endosomes/lysosomes in variant cells preincubated with LDL cholesterol but targeted to the Golgi complex in normal cells under these conditions. The reproducibility of this technique was validated in a blinded study. In addition, we performed mutation analysis of the NPC1 gene in NPC variant and "classical" NPC cell samples and found a high incidence of specific mutations within the cysteine-rich region of NPC1 in variants. We also found that 5 of the 12 variant cell samples had no apparent defect in NPC1 but were otherwise indistinguishable from other variant cells. This is a surprising result, since, in general, ∼90% of patients with NPC possess defects in NPC1. Our findings should be useful for the detection of NPC variants and also may provide significant new insight regarding NPC1 genotype/phenotype correlations.
AB - Niemann-Pick disease type C (NPC) is a fatal, autosomal recessive lipidosis characterized by lysosomal accumulation of unesterified cholesterol and multiple neurological symptoms, such as vertical supranuclear ophthalmoplegia, progressive ataxia, and dementia. More than 90% of cases of NPC are due to a defect in Niemann-Pick C1 (NPC1), a late endosomal, integral membrane protein that plays a role in cholesterol transport or homeostasis. Biochemical diagnosis of NPC has relied on the use of patient skin fibroblasts in an assay to demonstrate delayed low-density lipoprotein (LDL)-derived cholesterol esterification and a cytological technique-filipin staining-to demonstrate the intracellular accumulation of cholesterol. A small percentage of patients, referred to as "NPC variants," present with clinical symptoms of NPC but show near-normal results of these biochemical tests, making laboratory confirmation of NPC disease problematic. Here, we demonstrate that NPC-variant fibroblast samples can be detected as sphingolipid storage disease cells, using a fluorescent sphingolipid analog, BODIPY-lactosylceramide. This lipid accumulated in endosomes/lysosomes in variant cells preincubated with LDL cholesterol but targeted to the Golgi complex in normal cells under these conditions. The reproducibility of this technique was validated in a blinded study. In addition, we performed mutation analysis of the NPC1 gene in NPC variant and "classical" NPC cell samples and found a high incidence of specific mutations within the cysteine-rich region of NPC1 in variants. We also found that 5 of the 12 variant cell samples had no apparent defect in NPC1 but were otherwise indistinguishable from other variant cells. This is a surprising result, since, in general, ∼90% of patients with NPC possess defects in NPC1. Our findings should be useful for the detection of NPC variants and also may provide significant new insight regarding NPC1 genotype/phenotype correlations.
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U2 - 10.1086/320599
DO - 10.1086/320599
M3 - Article
C2 - 11349231
AN - SCOPUS:0034987028
VL - 68
SP - 1361
EP - 1372
JO - American Journal of Human Genetics
JF - American Journal of Human Genetics
SN - 0002-9297
IS - 6
ER -