Role of Rare and Low Frequency Variants in Gene-Alcohol Interactions on Plasma Lipid Levels

Background Alcohol intake influences plasma lipid levels and such effects may be modulated by genetic variants. Objective We aimed to characterize the role of aggregated rare and low-frequency variants in gene by alcohol consumption interactions associated with fasting plasma lipid levels. Design In the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) consortium, fasting plasma triglycerides (TG), and high- and low-density lipoprotein cholesterol (HDL-c and LDL-c) were measured in 34,153 European Americans from five discovery studies and 32,275 individuals from six replication studies. Rare and low-frequency protein coding variants (minor allele frequency ≤ 5%) measured by an exome array were aggregated by genes and evaluated by a gene-environment interaction (GxE) test and a joint test of genetic main and GxE interaction effects. Two dichotomous self-reported alcohol consumption variables, current drinker, defined as any recurrent drinking behavior, and regular drinker, defined as the subset of current drinkers who consume at least two drinks per week, were considered. Results We discovered and replicated 21 gene-lipid associations at 13 known lipid loci through the joint test. Eight loci ( PCSK9, LPA, LPL, LIPG, ANGPTL4, APOB, APOC3 and CD300LG ) remained significant after conditioning on the common index single nucleotide polymorphism (SNP) identified by previous genome-wide association studies, suggesting an independent role for rare and low-frequency variants at these loci. One significant gene-alcohol interaction on TG was discovered at a Bonferroni corrected significance level ( p -value <5×10 −5 ) and replicated ( p -value <0.013 for the interaction test) in SMC5 . Conclusions In conclusion, this study applied new gene-based statistical approaches to uncover the role of rare and low-frequency variants in gene-alcohol consumption interactions on lipid levels.