Genetic variation in the cholesterol transporter NPC1L1, ischaemic vascular disease, and gallstone disease

CLINICAL RESEARCH European Heart Journal (2015) 36, 1601–1608 doi:10.1093/eurheartj/ehv108 Coronary artery disease Genetic variation in the cholesterol transporter NPC1L1, ischaemic vascular disease, and gallstone disease 1 Department of Clinical Biochemistry, Rigshospitalet, Copenhagen University Hospitals and Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 9, Copenhagen, Denmark; 2The Copenhagen General Population Study, Herlev Hospital, Copenhagen University Hospitals and Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; 3Department of Clinical Biochemistry, Copenhagen University Hospitals and Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; and 4The Copenhagen City Heart Study, Frederiksberg Hospital, Copenhagen University Hospitals and Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark Received 17 September 2014; revised 29 January 2015; accepted 17 March 2015; online publish-ahead-of-print 4 April 2015 See page 1566 for the editorial comment on this article (doi:10.1093/eurheartj/ehv153) Aims Ezetimibe reduces plasma levels of low-density lipoprotein (LDL) cholesterol by inhibiting Niemann-Pick C1-Like protein 1 (NPC1L1), the transporter responsible for cholesterol uptake from the intestine into enterocytes and from the bile into hepatocytes. We tested the hypothesis that genetic variation in NPC1L1, mimicking the effect of ezetimibe, was associated with reduced risk of ischaemic vascular disease (IVD) and with increased risk of symptomatic gallstone disease. ..................................................................................................................................................................................... Methods We included 67 385 individuals from the general population. Of these, 5255 and 3886 individuals developed IVD or sympand results tomatic gallstone disease, respectively, during follow-up from 1977 to 2013. We genotyped four common NPC1L1 variants, previously associated with reduced LDL cholesterol levels, thus mimicking the effect of ezetimibe, and calculated a weighted genotype score. With increasing genotype score, LDL cholesterol decreased stepwise up to 3.5% (0.12 mmol/L) and total cholesterol up to 1.9% (0.11 mmol/L) (P-trend: 2 × 10212 and 2 × 1029). The cumulative incidence by age of IVD decreased, while that of symptomatic gallstone disease increased as a function of increasing genotype score (P-trend: 0.005 and 0.01). Hazard ratios for genotype scores ≥5.0 vs. ,2.0 were 0.82 (95% confidence interval: 0.70–0.95) for IVD and 1.22 (0.99–1.49) for gallstone disease (P-trend across genotype scores: 0.004 and 0.01). ..................................................................................................................................................................................... Conclusion Genetic variation in NPC1L1 is associated with a reduction in risk of IVD, with a corresponding reduction in LDL cholesterol, but with a concomitant increased risk of gallstone disease. These data support the hypothesis that treatment with ezetimibe protects against IVD but raise the question whether long-term treatment increases the risk of gallstone disease. ----------------------------------------------------------------------------------------------------------------------------------------------------------Keywords Genetics † Cholesterol † Cardiovascular diseases Introduction Treatment with statins reduces plasma levels of low-density lipoprotein (LDL) cholesterol and consequently protects against ischaemic vascular disease (IVD).1 Moreover, a growing body of evidence indicates that reductions in LDL cholesterol to levels lower than what is typically achieved by statins might further reduce the risk of IVD.2 To achieve such additional LDL cholesterol reduction, ezetimibe has been the focus of intense clinical and scientific interest as a potential add-on drug to statins.3 – 8 Ezetimibe inhibits Niemann-Pick C1-Like protein 1 (NPC1L1), a transporter responsible for intestinal sterol uptake into enterocytes, thereby reducing plasma levels of total and LDL cholesterol.9 Until the recent presentation of the data from the IMProved Reduction of Outcomes: Vytorin Efficacy International Trial (IMPROVE-IT), (http://www.eas-society.org/fileArch ive/IMPROVE%20IT%20-%20PRESENTATION%202014-11-17.pdf, accessed 27 March 2015) it has been unclear, however, whether the addition of ezetimibe to conventional statin treatment confers additional protection against IVD.10,11 Ezetimibe has been safe and well-tolerated in randomized controlled trials, with no major adverse effects reported (http://www. eas-society.org/fileArchive/IMPROVE%20IT%20-%20PRESENTATION * Corresponding author. Tel: +45 3545 4159, Fax: +45 3545 4160, Email: Published on behalf of the European Society of Cardiology. All rights reserved. & The Author 2015. For permissions please email: . Bo Kobberø Lauridsen 1, Stefan Stender 1, Ruth Frikke-Schmidt 1,2, Børge G. Nordestgaard 2,3,4, and Anne Tybjærg-Hansen 1,2,4* 1602 LDL cholesterol levels also was associated with reduced risk of IVD and with increased risk of symptomatic gallstone disease. We genotyped four common variants in NPC1L1, previously suggested to be associated with reduced LDL cholesterol levels,18,19 in two studies of the Danish general population totalling 67 385 participants, of whom 5255 developed IVD and 3886 developed symptomatic gallstone disease from 1977 through 2013. Methods Studies were approved by institutional review boards and Danish ethical committees, and were conducted according to the Declaration of Helsinki. Written informed consent was obtained from participants. All participants were white and of Danish descent, as determined by the National Danish Civil Registration System. Participants We included participants in two similar studies of the Danish general population, The Copenhagen General Population Study (CGPS) and The Copenhagen City Heart Study (CCHS). Combining these two studies yielded a total of 67 385 participants, of whom 5255 developed IVD (myocardial infarction and/or ischaemic stroke) and 3886 developed symptomatic gallstone disease. DNA was available on all participants, and lipid parameters were available on .98%. For additional information on study populations, endpoints, laboratory analysis and covariates, see Supplementary material online. Genotyping We genotyped four common variants (minor allele frequency .5%) in NPC1L1: 2133A.G (rs17655652); 218C.A (rs41279633); L272L C.G (rs2072183); and V1296V T.C (rs217434), previously shown to be associated with plasma levels of LDL cholesterol.18,19 Of these, 133A.G has been reported to be functional per se,20 while L272L is in linkage disequilibrium with a known functional variant, 2762T.C in a putative Ying Yang1 binding site,21 and 218C.A is in close proximity (...truncated)