Variants at the APOE/C1/C2/C4 Locus Modulate Cholesterol Efflux Capacity Independently of High‐Density Lipoprotein Cholesterol

Abstract

Background Macrophage cholesterol efflux to high‐density lipoproteins (HDLs) is the first step of reverse cholesterol transport. The cholesterol efflux capacity (CEC) of HDL particles is a protective risk factor for coronary artery disease independent of HDL cholesterol levels. Using a genome‐wide association study approach, we aimed to identify pathways that regulate CEC in humans. Methods and Results We measured CEC in 5293 French Canadians. We tested the genetic association between 4 CEC measures and genotypes at >9 million common autosomal DNA sequence variants. These analyses yielded 10 genome‐wide significant signals (P<6.25×10−9) representing 7 loci. Five of these loci harbor genes with important roles in lipid biology (CETP, LIPC, LPL, APOA1/C3/A4/A5, and APOE/C1/C2/C4). Except for the APOE/C1/C2/C4 variant (rs141622900, Pnonadjusted=1.0×10−11; Padjusted=8.8×10−9), the association signals disappear when correcting for HDL cholesterol and triglyceride levels. The additional 2 significant signals were near the PPP1CB/PLB1 and RBFOX3/ENPP7 genes. In secondary analyses, we considered candidate functional variants for 58 genes implicated in HDL biology, as well as 239 variants associated with blood lipid levels and/or coronary artery disease risk by genome‐wide association study. These analyses identified 27 significant CEC associations, implicating 5 additional loci (GCKR, LIPG, PLTP, PPARA, and TRIB1). Conclusions Our genome‐wide association study identified common genetic variation at the APOE/C1/C2/C4 locus as a major determinant of CEC that acts largely independently of HDL cholesterol. We predict that HDL‐based therapies aiming at increasing CEC will be modulated by changes in the expression of apolipoproteins in this gene cluster.

Keywords

• HDL efflux
• genome‐wide association study
• high‐density lipoprotein cholesterol