A genome-wide association study in Europeans and South Asians identifies five new loci for coronary artery disease

Study Hypothesis Recently, genome-wide association studies (GWAS) have identified several common variants associated with increased risk of coronary artery disease (CAD) and myocardial infarction (MI) by 10% to 30%. The authors state that these loci explain only a small proportion of the predicted genetic risk and that all of the current loci for CAD and MI by GWAS have been discovered in European populations. The authors hypothesized that discovery of new susceptibility loci of smaller effect sizes would be aided by conducting much larger studies in addition to an emphasis on early-onset CAD and clearly defined clinical end points. Therefore, they assembled the Coronary Artery Disease (C4D) Genetics Consortium.1 ### How Was the Hypothesis Tested? The authors performed a meta-analysis of 4 large GWAS of CAD, 2 of European ancestry (PROCARDIS and HPS) and 2 of South Asian ancestry (PROMIS and LOLLIPOP), with ≈575 000 genotyped single-nucleotide polymorphisms (SNPs) in a discovery data set comprising 15 420 individuals with CAD (cases) (8424 Europeans and 6996 South Asians) and 15 062 control subjects. They observed little evidence for ancestry-specific associations, supporting the use of combined analyses. Furthermore, the authors state that because all individuals were genotyped on the same platform (whole-genome Illumina BeadChips), a meta-analysis of actual genotypes rather than imputed data enabled analysis of low-frequency variants (1% to 5%), which have been excluded from GWAS either because of sample size or because imputation has been required to combine data from different genotyping platforms. After the meta-analysis, they selected 59 SNPs from 50 loci that showed potential new associations from the meta-analysis of the European and South Asian studies (41 SNPs; P