ABCMdb

ABCA1 p.Arg1851*

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[hide] Exome sequencing identifies 2 rare variants for lo... Circ Cardiovasc Genet. 2012 Oct 1;5(5):538-46. doi: 10.1161/CIRCGENETICS.112.963264. Epub 2012 Aug 25. Reddy MV, Iatan I, Weissglas-Volkov D, Nikkola E, Haas BE, Ruel MJ, Sinsheimer JS, Genest J, Pajukanta P
Exome sequencing identifies 2 rare variants for low high-density lipoprotein cholesterol in an extended family.
Circ Cardiovasc Genet. 2012 Oct 1;5(5):538-46. doi: 10.1161/CIRCGENETICS.112.963264. Epub 2012 Aug 25., [PMID:22923419]

Abstract [show]
Background- Exome sequencing is a recently implemented method to discover rare mutations for Mendelian disorders. Less is known about its feasibility to identify genes for complex traits. We used exome sequencing to search for rare variants responsible for a complex trait, low levels of serum high-density lipoprotein cholesterol (HDL-C). Methods and Results- We conducted exome sequencing in a large French-Canadian family with 75 subjects available for study, of which 27 had HDL-C values less than the fifth age-sex-specific population percentile. We captured approximately 50 Mb of exonic and transcribed sequences of 3 closely related family members with HDL-C levels less than the fifth age-sex percentile and sequenced the captured DNA. Approximately 82 000 variants were detected in each individual, of which 41 rare nonsynonymous variants were shared by the sequenced affected individuals after filtering steps. Two rare nonsynonymous variants in the ATP-binding cassette, subfamily A (ABC1), member 1 (ABCA1), and lipoprotein lipase genes predicted to be damaging were investigated for cosegregation with the low HDL-C trait in the entire extended family. The carriers of either variant had low HDL-C levels, and the individuals carrying both variants had the lowest HDL-C values. Interestingly, the ABCA1 variant exhibited a sex effect which was first functionally identified, and, subsequently, statistically demonstrated using additional French-Canadian families with ABCA1 mutations. Conclusions- This complex combination of 2 rare variants causing low HDL-C in the extended family would not have been identified using traditional linkage analysis, emphasizing the need for exome sequencing of complex lipid traits in unexplained familial cases.

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38 Genotype by sex interaction We included the extended family together with 10 additional families with previously identified mutations in ABCA16-8 in a gene-sex interaction analysis, comprising 200 individuals and 9 different mutations in ABCA1 (DelED1893, G616V, K776N, N1800H, Q2210H, R1851X, R2084X, R909X and S1731C). Login to comment
41 Genotype by Sex Interaction We included the extended family together with 10 additional families with previously identified mutations in ABCA16 -8 in a gene-sex interaction analysis, comprising 200 individuals and 9 different mutations in ABCA1 (DelED1893, G616V, K776N, N1800H, Q2210H, R1851X, R2084X, R909X, and S1731C). Login to comment
158 Figure 3 shows the age-sex specific population HDL-C percentiles by ABCA1 genotypes and sex in 200 French-Canadian family members from 11 French-Canadian families with different ABCA1 mutations (DelED1893, G616V, K776N, N1800H, Q2210H, R1851X, R2084X, R909X, and S1731C). Login to comment

[hide] An ABCA1 truncation shows no dominant negative eff... Biochem Biophys Res Commun. 2011 Jun 10;409(3):400-5. Epub 2011 May 7. Sorrenson B, Suetani RJ, Bickley VM, George PM, Williams MJ, Scott RS, McCormick SP
An ABCA1 truncation shows no dominant negative effect in a familial hypoalphalipoproteinemia pedigree with three ABCA1 mutations.
Biochem Biophys Res Commun. 2011 Jun 10;409(3):400-5. Epub 2011 May 7., [PMID:21575609]

Abstract [show]
The ATP binding cassette transporter (ABCA1) A1 is a key determinant of circulating high density lipoprotein cholesterol (HDL-C) levels. Mutations in ABCA1 are a major genetic contributor to low HDL-C levels within the general population. Following the finding of three different ABCA1 mutations, p.C978fsX988, p.T1512M and p.N1800H in a subject with hypoalphalipoproteinemia, we aimed to establish whether the p.C978fsX988 truncation exerted a dominant negative effect on the full-length ABCA1 alleles within family members as has been reported for other ABCA1 truncations. Characterisation of the p.C978fsX988 mutant in transfected HEK 293 cells showed it to be expressed as a GFP fusion protein but lacking in cholesterol efflux function. This was in keeping with results from cholesterol efflux assays in the fibroblasts of p.C978fsX988 carriers which also showed impaired efflux. Allele- specific quantification of p.C978fsX988 mRNA and analysis of ABCA1 protein levels in the fibroblasts of p.C978fsX988 heterozygotes showed negligible levels of mRNA and protein expression. There was no evidence of a dominant negative effect on wildtype or p.N1800H protein levels. We conclude that in the case of the p.C978fsX988 truncated mutant a lack of expression precludes it from having a dominant negative effect.

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20 Expression and functional analysis of truncated ABCA1 mutants in isolation is limited to the ABCA1 p.R1851X truncation [9,10]. Login to comment

[hide] Functional mutations of the ABCA1 gene in subjects... Atherosclerosis. 2006 Oct;188(2):281-91. Epub 2005 Dec 15. Alrasadi K, Ruel IL, Marcil M, Genest J
Functional mutations of the ABCA1 gene in subjects of French-Canadian descent with HDL deficiency.
Atherosclerosis. 2006 Oct;188(2):281-91. Epub 2005 Dec 15., [PMID:16343503]

Abstract [show]
Mutations in the ABCA1 gene cause defective cellular lipid efflux and severe familial HDL deficiency. We examined the prevalence of mutations at the ABCA1 gene in 58 unrelated probands of French-Canadian descent with HDL deficiency (HDL-C<5th percentile). A defective cellular cholesterol or phospholipid efflux (<75% and <70% of normal controls, respectively) was identified in 14/58 (24%) of subjects. Using direct sequencing of the ABCA1 gene, we found mutations in 12/58 ( approximately 20%) of subjects. Four probands were previously identified with diverse ABCA1 gene defects. However, we identified a novel frameshift mutation (F1840L, L1869X); a proband was heteroallelic for the N1800H mutation, previously reported in a case of Tangier disease, and a novel missense mutation (Q2210H); a novel variant (G616V), predicted to impart a functional defect in the protein, was also found in another proband. Three probands had the S1731C mutation, while two others had the R1851X and K776N documented mutations, respectively. Taken together, these data suggest that approximately 20% of French-Canadian patients with severe HDL deficiency are associated with a defective ABCA1. Interestingly, in two families studied, mutations in the ABCA1 gene did not segregate with the lipid efflux defect, suggesting that other proteins are involved in the ABCA1-mediated cellular lipid efflux.

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6 Three probands had the S1731C mutation, while two others had the R1851X and K776N documented mutations, respectively. Login to comment
86 Table 2 Mutations of the ABCA1 gene in French-Canadian probands with HDL deficiency and defective cellular lipid efflux Probandsa Gene region Nucleotide change Amino acid change Predicted effect by Polyphenb Reference ABE Exon 48 C6370T R2084X Truncated protein [8,9] MGA Exon 14 del 2017-2019 del L693 Probably damaging [8,9] ALA Exon 41 del 5618-5623 del ED1893,4 Probably damaging [8,9] RLA Exon 18 C2665T R909X Truncated protein [8,9] RDU Exon 41 C5864T R1851X Truncated protein [4] SBO Exon 40 A5711C N1800H Possibly damaging [27] Exon 49 G6943C Q2210H Probably damaging - RPH Exon 14 G2160T G616V Probably damaging - GOB Exon 41 del 5833 fs F1840L, L1869X Truncated protein - LNO Exon 38 C5505G S1731C Possibly damaging [4] VDU Exon 38 C5505G S1731C Possibly damaging [4] RRI Exon 38 C5505G S1731C Possibly damaging [4] PCH Exon 16 G2641C K776N Possibly damaging [5] GCH - - - - - LBO - - - - - a Probands refer to subjects ID # 301 in the pedigrees. b Polyphen computer software (http://www.bork.embl-heidelberg.de/polphen/). Login to comment
110 In the remaining eight probands, we identified a previously reported mutation [4], R1851X, in proband RDU that perfectly segregated with the low HDL-C trait in the kindred (Fig. 2A). Login to comment

[hide] Novel polypyrimidine variation (IVS46: del T -39..... Circ Res. 2003 Nov 14;93(10):1006-12. Epub 2003 Oct 23. Hong SH, Rhyne J, Miller M
Novel polypyrimidine variation (IVS46: del T -39...-46) in ABCA1 causes exon skipping and contributes to HDL cholesterol deficiency in a family with premature coronary disease.
Circ Res. 2003 Nov 14;93(10):1006-12. Epub 2003 Oct 23., [PMID:14576201]

Abstract [show]
Recent studies have implicated mutations in the ATP-binding cassette transporter A1, ABCA1, as a cause of Tangier disease (TD) and familial hypoalphalipoproteinemia (FHA). We investigated a proband with very low levels of high-density lipoprotein cholesterol (HDL-C, 6 mg/dL) and a history of premature coronary heart disease (CHD). Sequencing of the ABCA1 gene revealed 2 distinct variants. The first mutation was a G5947A substitution (R1851Q). The second mutation was a single-nucleotide deletion of thymidine in a polypyrimidine tract located 33 to 46 bps upstream to the start of exon 47. This mutation does not involve the 3' acceptor splice site and is outside the lariat branchpoint sequence (IVS46: del T -39...-46). Amplification of cDNA obtained in cultured fibroblasts of the proband and affected family member revealed an abnormally spliced cDNA sequence with skipping of exon 47. These variants were not identified in over 400 chromosomes of healthy whites. Compound heterozygotes (n=4) exhibited the lowest HDL-C (11+/-5 mg/dL) and ApoA-I (35+/-15 mg/dL) compared with wild-type (n=25) (HDL-C 51+/-14 mg/dL; ApoA-I 133+/-21 mg/dL) (P<0.0005) or subjects affected with either R1851Q (n=6) (HDL-C 36+/-8; ApoA-I 117+/-19) or IVS46: del T -39...-46 (n=5) (HDL-C 31+9; ApoA-I 115+28 (P<0.01). These data suggest that polypyrimidine tract variation may represent a novel mechanism for altered splicing and exon skipping that is independent of traditional intronic variants as previously identified in acceptor/donor splice regions or the lariat branchpoint domain.

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100 between premature CHD and either increased carotid intimal-medial thickness or reduced ABCA1-mediated cholesterol efflux.25-27 The premature CHD identified in the proband extends previous observational data in normolipidemic indi- viduals1-3 and may not only reflect alterations in RCT but other recently identified antiatherogenic effects potentially subserved by HDL including reduced ischemic-reperfusion injury28 and improved vascular function.29 To date, only a small proportion of ABCA1 variants have been characterized in pivotal regions (eg, extracellular loop, transmembrane domain, nucleotide binding folds, C-terminus) that when altered, result in marked reduction in ABCA1 activity and/or function.6,7 The G5947A/ R1851Q mutation occurs within the extracellular loop proximal to the final transmembrane spanner and bears regional similarity to the C5946T/R1851X variant recently reported in a compound heterozygote with TD.30 Variants located within the extracellular loop (between amino acids 1370 to 1650) have been shown to adversely affect the interaction of ABCA1 and ApoA-I resulting in reduced cholesterol efflux.31 Whether distal variants (eg, N1800H, R1851G) exhibit similar interactions with ApoA-I has not been studied, but the marked reductions in HDL-C that have been observed in affected subjects suggest that binding may be similarly disrupted. Login to comment
95 Ho Hong et al Exon Skipping in ABCA1 and HDL-C Deficiency between premature CHD and either increased carotid intimal-medial thickness or reduced ABCA1-mediated cholesterol efflux.25-27 The premature CHD identified in the proband extends previous observational data in normolipidemic indi- viduals1-3 and may not only reflect alterations in RCT but other recently identified antiatherogenic effects potentially subserved by HDL including reduced ischemic-reperfusion injury28 and improved vascular function.29 To date, only a small proportion of ABCA1 variants have been characterized in pivotal regions (eg, extracellular loop, transmembrane domain, nucleotide binding folds, C-terminus) that when altered, result in marked reduction in ABCA1 activity and/or function.6,7 The G5947A/ R1851Q mutation occurs within the extracellular loop proximal to the final transmembrane spanner and bears regional similarity to the C5946T/R1851X variant recently reported in a compound heterozygote with TD.30 Variants located within the extracellular loop (between amino acids 1370 to 1650) have been shown to adversely affect the interaction of ABCA1 and ApoA-I resulting in reduced cholesterol efflux.31 Whether distal variants (eg, N1800H, R1851G) exhibit similar interactions with ApoA-I has not been studied, but the marked reductions in HDL-C that have been observed in affected subjects suggest that binding may be similarly disrupted. Login to comment

[hide] Genetics of HDL regulation in humans. Curr Opin Lipidol. 2003 Jun;14(3):273-9. Miller M, Rhyne J, Hamlette S, Birnbaum J, Rodriguez A
Genetics of HDL regulation in humans.
Curr Opin Lipidol. 2003 Jun;14(3):273-9., [PMID:12840658]

Abstract [show]
PURPOSE OF REVIEW: To review gene regulation of HDL-cholesterol and discuss molecular abnormalities in HDL candidate genes that may lead to human pathologic states. RECENT FINDINGS: The inverse association between HDL-cholesterol and vascular disease, especially coronary heart disease, has long been recognized, but understanding gene regulation of HDL in humans gained considerable momentum following the identification of ABCA1 as playing a pivotal role in reverse cholesterol transport. Recent data suggest that potentially important targets for upregulating HDL in humans include upregulators of ABCA1 and APOA1 (e.g. peroxisome proliferator activated receptor and liver X receptor agonists) and downregulators of CETP (e.g. JTT-705). A host of other nuclear receptors under investigation in animal models may advance to human testing in the near future. SUMMARY: Disorders affecting HDL metabolism are complex because monogenic disorders causing low HDL do not necessarily correlate with premature vascular disease. To date, pathologic phenotypes have only been deduced among several HDL candidate genes. Understanding the genetic underpinnings associated with variant HDL and reverse cholesterol transport provides an exceptional opportunity to identify novel agents that may optimize this process and reduce vascular event rates beyond currently available LDL lowering therapies.

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67 TD 3` deletion (intron 38) truncated truncation [61] 5587 C/G 38 S1731C extracellular [68] TD 5793 A/C 40 N1800H extracellular loop, sm [65] FHA 5946 C/T 41 R1851X truncation [75..] FHA 6068 del 42 del 1893-1894(E,D) cytoplasmic [63] TD 6152 (14bp Ins) (42-43) truncated truncation [67] 6316 A/G 44 K1974R cytoplasmic [67] 6421 T/C 45 F2009S cytoplasmic [9] TD 6636 C/T 47 R2081W cytoplasmic [64] FHA 6825 C/T 49 R2144X cytoplasmic [63] TD 6825 del C 49 2145X truncation [62] FHA 6844 C/T 49 P2150L cytoplasmic [62] 6898 C/T 49 P2168L cytoplasmic [67] TD CTC6952-4TT 49 2203X truncation [62] TD 6968 (4bp Ins) 49 2215X, truncated PDZ binding (cyto) [65] *Location in accordance with Santamaria-Fojo et al. (Proc Natl Acad Sci U S A 2000; 97:7987-7992). Login to comment

[hide] Truncation mutations in ABCA1 suppress normal upre... J Lipid Res. 2002 Nov;43(11):1939-49. Wellington CL, Yang YZ, Zhou S, Clee SM, Tan B, Hirano K, Zwarts K, Kwok A, Gelfer A, Marcil M, Newman S, Roomp K, Singaraja R, Collins J, Zhang LH, Groen AK, Hovingh K, Brownlie A, Tafuri S, Genest J Jr, Kastelein JJ, Hayden MR
Truncation mutations in ABCA1 suppress normal upregulation of full-length ABCA1 by 9-cis-retinoic acid and 22-R-hydroxycholesterol.
J Lipid Res. 2002 Nov;43(11):1939-49., [PMID:12401893]

Abstract [show]
Mutations in ABCA1 uniformly decrease plasma HDL-cholesterol (HDL-C) and reduce cholesterol efflux, yet different mutations in ABCA1 result in different phenotypic effects in heterozygotes. For example, truncation mutations result in significantly lower HDL-C and apoliprotein A-I (apoA-I) levels in heterozygotes compared with nontruncation mutations, suggesting that truncation mutations may negatively affect the wild-type allele. To specifically test this hypothesis, we examined ABCA1 protein expression in response to 9-cis-retinoic acid (9-cis-RA) and 22-R-hydroxycholesterol (22-R-OH-Chol) in a collection of human fibroblasts representing eight different mutations and observed that truncation mutations blunted the response to oxysterol stimulation and dominantly suppressed induction of the remaining full-length allele to 5-10% of wild-type levels. mRNA levels between truncation and nontruncation mutations were comparable, suggesting that ABCA1 expression was suppressed at the protein level. Dominant negative activity of truncated ABCA1 was recapitulated in an in vitro model using transfected Cos-7 cells. Our results suggest that the severe reduction of HDL-C in patients with truncation mutations may be at least partly explained by dominant negative suppression of expression and activity of the remaining full-length ABCA1 allele. These data suggest that ABCA1 requires a physical association with itself or other molecules for normal function and has important pharmacogenetic implications for individuals with truncation mutations.

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27 One new heterozygous subject is included in this study who is from a new TD kindred ( JP2) and contains the truncation mutation R1851X (13). Login to comment
163 Coexpression of FLAG-tagged ABCA1 truncated at amino acid 1851 (R1851X) significantly inhibited efflux compared with cells transfected with a single copy of wild-type ABCA1 (P Ͻ 0.001, n ϭ 3, Fig. 5B). Login to comment
164 Finally, cells were cotransfected with Xpress-tagged wild-type and FLAG-tagged missense ABCA1 (N1611D). Login to comment
196 Cos-7 cells were transfected singly with vector (mock), Xpress-tagged wild-type human ABCA1 cDNA (WT/Xpress), or cotransfected with FLAG-tagged wild-type ABCA1 (WT/Xpress ϩ WT/FLAG), FLAG-tagged ABCA1 containing the N1611D mutation (WT/Xpress ϩ N1611D/FLAG), or with FLAG-tagged ABCA1 containing the R1851X mutation (WT/Xpress ϩ R1851X/FLAG). Login to comment
197 Cos-7 cells were transfected singly with vector (mock), Xpress-tagged wild-type human ABCA1 cDNA (WT/Xpress), or cotransfected with FLAG-tagged wild-type ABCA1 (WT/Xpress WT/FLAG), FLAG-tagged ABCA1 containing the N1611D mutation (WT/Xpress N1611D/FLAG), or with FLAG-tagged ABCA1 containing the R1851X mutation (WT/Xpress R1851X/FLAG). Login to comment

[hide] Dominant expression of ATP-binding cassette transp... Biochem Biophys Res Commun. 2002 Aug 23;296(3):625-30. Ohama T, Hirano K, Zhang Z, Aoki R, Tsujii K, Nakagawa-Toyama Y, Tsukamoto K, Ikegami C, Matsuyama A, Ishigami M, Sakai N, Hiraoka H, Ueda K, Yamashita S, Matsuzawa Y
Dominant expression of ATP-binding cassette transporter-1 on basolateral surface of Caco-2 cells stimulated by LXR/RXR ligands.
Biochem Biophys Res Commun. 2002 Aug 23;296(3):625-30., [PMID:12176027]

Abstract [show]
ATP-binding cassette transporter-1 (ABCA1) is a cause of Tangier disease, which is a familial deficiency of plasma high density lipoproteins (HDL). This molecule is known to be expressed in the multiple tissues and organs including small intestines, liver, and macrophages in the blood vessels. Recent in vivo studies suggested that ABCA1 plays some roles in the flux of cholesterol in the intestines. One of the major questions to understand the roles of ABCA1 in the intestines is the expression pattern in the intestinal epithelial cells. To address this issue, we have investigated the expression and regulation of ABCA1 in Caco-2 cells cultured on Transwell as a model, especially focusing on possible polarized expression of ABCA1. The expression of ABCA1 was up-regulated during the differentiation and under the stimulation of LXR/RXR by the addition of 9-cis-retinoic acid (9-cis-RA) and 22-R-hydroxycholesterol (22-OH). Apolipoprotein-AI-mediated cholesterol efflux was dominant toward the basolateral side of polarized cells when stimulated by 9-cis-RA and 22-OH. The cell surface biotinylation experiment followed by Western blot analyses demonstrated a markedly dominant expression of ABCA1 on the basolateral surface, which was clearly confirmed by the confocal laser scanning microscopy. In conclusion, the present study demonstrates that ABCA1 is dominantly expressed on the basolateral surface of Caco-2 cells tested, suggesting that this molecule may play a role in the basolateral movement of cholesterol at least when stimulated by LXR/RXR ligands.

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40 In these control experiments, we used the fibroblasts from a homozygous patient with Tangier disease carrying R1851X mutation [10] lacking the epitope for Ab ABCA12177 as a negative control. Login to comment

[hide] Expression and functional analyses of novel mutati... Biochem Biophys Res Commun. 2002 Jan 18;290(2):713-21. Nishida Y, Hirano K, Tsukamoto K, Nagano M, Ikegami C, Roomp K, Ishihara M, Sakane N, Zhang Z, Tsujii Ki K, Matsuyama A, Ohama T, Matsuura F, Ishigami M, Sakai N, Hiraoka H, Hattori H, Wellington C, Yoshida Y, Misugi S, Hayden MR, Egashira T, Yamashita S, Matsuzawa Y
Expression and functional analyses of novel mutations of ATP-binding cassette transporter-1 in Japanese patients with high-density lipoprotein deficiency.
Biochem Biophys Res Commun. 2002 Jan 18;290(2):713-21., [PMID:11785958]

Abstract [show]
ATP-binding cassette transporter-1 (ABCA1) gene is mutated in patients with familial high-density lipoprotein deficiency (FHD). In order to know the molecular basis for FHD, we characterized three different ABCA1 mutations associated with FHD (G1158A/A255T, C5946T/R1851X, and A5226G/N1611D) with respect to their expression in the passaged fibroblasts from the patients and in the cells transfected with the mutated cDNAs. Fibroblasts from the all patients showed markedly decreased cholesterol efflux to apolipoprotein (apo)-Al. In the fibroblasts homozygous for G1158A/A255T, the immunoreactive mass of ABCA1 could not be detected, even when stimulated by 9-cis-retinoic acid and 22-R-hydroxycholesterol. In the fibroblasts homozygous for C5946T/R1851X, ABCA1 mRNA was comparable. Because the mutant ABCA1 protein (R1851X) was predicted to lack the epitope for the antibody used, we transfected FLAG-tagged truncated mutant (R1851X/ABCA1-FLAG) cDNA into Cos-7 cells, showing that the mutant protein expression was markedly reduced. The expression of N1611D ABCA1 protein was comparable in both fibroblasts and overexpressing cells, although cholesterol efflux from the cells was markedly reduced. These data indicated that, in the three patients investigated, the abnormalities and dysfunction of ABCA1 occurred at the different levels, providing important information about the expression, regulation, and function of ABCA1.

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1 In order to know the molecular basis for FHD, we characterized three different ABCA1 mutations associated with FHD (G1158A/ A255T, C5946T/R1851X, and A5226G/N1611D) with respect to their expression in the passaged fibroblasts from the patients and in the cells transfected with the mutated cDNAs. Login to comment
3 In the fibroblasts homozygous for C5946T/R1851X, ABCA1 mRNA was comparable. Login to comment
4 Because the mutant ABCA1 protein (R1851X) was predicted to lack the epitope for the antibody used, we transfected FLAG-tagged truncated mutant (R1851X/ABCA1-FLAG) cDNA into Cos-7 cells, showing that the mutant protein expression was markedly reduced. Login to comment
59 TABLE 1 Clinical Profiles of Patients with Familial HDL Deficiency Case 1 Case 2 Case 3 ABCA1 substitutions found (nt/aa) G1158A/A255T C5946T/R1851X A5226G/N1611D Age (years)/sex (M, F) 56/M 71/F 53/F Total cholesterol (mmol/L) 0.72 1.47 2.7 HDL-cholesterol (mmol/L) 0.16 0.05 0.11 Triglyceride (mmol/L) 2.6 3.27 1.75 Apo-Al (mg/dL) 3.9 5.0 11.0 Atherosclerosis ϩ ϩ ϩ Typical TD phenotype ϩ ϩ - Cholesterol efflux (% of control) 5.0 2.0 7.0 Note. Login to comment
105 R1851X appeared to lack the second nucleotide binding domain. Login to comment
109 We could not find the G1158A/A255T substitution in 48 unrelated Americans or 176 Japanese control subjects (data not shown). Login to comment
111 This mutation caused a premature stop at the codon 1851 (R1851X), resulting that the predicted ABCA1 protein was truncated from lacking the second nucleotide binding domain (NBD) (Figs. 1B and 2). Login to comment
116 In Cases 2 (Ho/ R1851X) and 3 (Ho/N1611D), the expression of mRNA did not appear to be altered with and without the stimulation (Figs. 3A and 3B). Login to comment
120 As it was noted that the predicted mutant ABCA1 (R1851X) lacked the epitope for the antibody we used, we could not see any immunoreactive mass in fibroblasts from Case 2 (Ho/ R1851X). Login to comment
125 It was striking that the protein expression of cDNA construct carrying the truncated mutation (R1851X) was extremely low, though we could see the expected band with smaller size. Login to comment
130 As expected, no significant cholesterol efflux could be detected from cells transfected with R1851X/ ABCA1-FLAG cDNA. Login to comment
145 In Case 2, we found another novel mutation resulting in the presence of truncated ABCA1 which lacks the second NBD (R1851X). Login to comment
146 Our transfection study demonstrated an interesting data to show that the expression level of truncated mutant (R1851X) was much lower than those of other mutants and wild type tested. Login to comment
151 Based upon the results of our transfection experiment (Fig. 3), we speculated that ABCA1 expression was severely impaired at the protein level in Case 2 (Ho/R1851X). Login to comment
58 TABLE 1 Clinical Profiles of Patients with Familial HDL Deficiency Case 1 Case 2 Case 3 ABCA1 substitutions found (nt/aa) G1158A/A255T C5946T/R1851X A5226G/N1611D Age (years)/sex (M, F) 56/M 71/F 53/F Total cholesterol (mmol/L) 0.72 1.47 2.7 HDL-cholesterol (mmol/L) 0.16 0.05 0.11 Triglyceride (mmol/L) 2.6 3.27 1.75 Apo-Al (mg/dL) 3.9 5.0 11.0 Atherosclerosis af9; af9; af9; Typical TD phenotype af9; af9; afa; Cholesterol efflux (% of control) 5.0 2.0 7.0 Note. Login to comment
104 R1851X appeared to lack the second nucleotide binding domain. Login to comment
114 In Cases 2 (Ho/ R1851X) and 3 (Ho/N1611D), the expression of mRNA did not appear to be altered with and without the stimulation (Figs. 3A and 3B). Login to comment
118 As it was noted that the predicted mutant ABCA1 (R1851X) lacked the epitope for the antibody we used, we could not see any immunoreactive mass in fibroblasts from Case 2 (Ho/ R1851X). Login to comment
123 It was striking that the protein expression of cDNA construct carrying the truncated mutation (R1851X) was extremely low, though we could see the expected band with smaller size. Login to comment
128 As expected, no significant cholesterol efflux could be detected from cells transfected with R1851X/ ABCA1-FLAG cDNA. Login to comment
143 In Case 2, we found another novel mutation resulting in the presence of truncated ABCA1 which lacks the second NBD (R1851X). Login to comment
144 Our transfection study demonstrated an interesting data to show that the expression level of truncated mutant (R1851X) was much lower than those of other mutants and wild type tested. Login to comment
149 Based upon the results of our transfection experiment (Fig. 3), we speculated that ABCA1 expression was severely impaired at the protein level in Case 2 (Ho/R1851X). Login to comment