APOE and vascular disease: Sequencing and genotyping in general population cohorts

Background and aims: The apolipoprotein E(APOE) epsilon 2/epsilon 3/epsilon 4 polymorphism plays a central role in lipid metabolism, vascular disease and dementia. The impact of the full range of structural genetic variation in APOE for lipids, lipoproteins and apolipoproteins and for vascular disease in the general population is not known. Methods: We systematically sequenced APOE in 10,296 individuals from the Copenhagen City Heart Study and genotyped nine rare variants (frequency >= 2/10,296) in 95,227 individuals from the Copenhagen General Population Study. The UK Biobank was used for validation of common APOE variants. Results: Rare mutations in APOE, predicted to be deleterious, are present in 1 in 257 individuals in the general population. In the meta-analysis, multifactorially adjusted hazard ratios (95% confidence intervals) for epsilon 44 and epsilon 22 versus epsilon 33 were 1.15 (1.04-1.26) and 1.02 (0.83-1.24) for ischemic cerebrovascular disease (ICVD), 1.11 (1.04-1.19) and 0.94 (0.83-1.08) for ischemic heart disease (IHD) and 1.03 (0.89-1.17) and 1.49 (1.20-1.87) for peripheral arterial disease (PAD). A multifactorially and epsilon 2/epsilon 3/epsilon 4 adjusted weighted allele score on the continuous scale including all common and rare structural variants showed that for individuals with genetically predicted high plasma apoE and remnant cholesterol the risk for PAD was increased. Conclusions: APOE variants with high apoE, triglycerides, and remnant cholesterol are associated with PAD, whereas common APOE variants with high LDL cholesterol, triglycerides and remnant cholesterol are associated with IHD. APOE variants with low apoE are associated with increased risk of ICVD. These findings highlight that both rare and common structural variations in APOE play a role in vascular disease.