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 AND RESULTS: We included 67 385 individuals from the general population. Of these, 5255 and 3886 individuals developed IVD or symptomatic 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 × 10(-12) and 2 × 10(-9)). 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.