Genetics of type 2 diabetes and coronary artery disease and their associations with twelve cardiometabolic traits in the United Arab Emirates population

The United Arab Emirates (UAE) population has a high rate of type 2 diabetes mellitus (T2DM) and other metabolic risk factors for coronary artery disease (CAD). Previous studies have indicated strong genetic associations between T2DM and CAD. The objective of this study was to replicate previously reported significant genetic associations for T2DM and CAD which were in a genome-wide significance level in a cohort from the Arab population of the UAE, and to investigate the associations of these loci with twelve cardiometabolic traits that may influence the development of T2DM and CAD. A total of nine hundreds and fourteen Emiratis were recruited to this study to investigate associations of 101 loci for T2DM (422 patients and 455 controls), and 53 loci for CAD (160 patients and 245 controls), using logistic regression models which incorporating possible confounding factors. Results are presented using odds ratios with their corresponding 95% confidence intervals and p-values. Linear regression models, which included possible covariates were applied to determine any associations between the T2DM and CAD reported loci with the twelve cardiometabolic traits and results were presented as effect sizes (beta), standard errors, and p-values. Furthermore, the overall risks for all the loci found to be associated with T2DM and CAD were determined using the cumulative effects of the risk alleles. For those found to be associated with the twelve cardiometabolic traits, risks were determined using calculations of their polygenic risk scores. The mean age of the T2DM group was 61.5 ± 11.3 and of the CAD group was 66.2 ± 9.3 years. The prevalence of most of the cardiovascular disease risk factors in this cohort were high: mean body mass index (BMI) = 29.4, T2DM (51.9%), hypertension (60.9%), dyslipidemia (68.8%), and smoking (47.9%). All individuals who were tested for CAD (n = 405) also had a diagnosis of T2DM. The highest association variant for T2DM was in SNP rs1977833 in HHEX (p = 0.0016, OR = 0.56 for allele A), which is a multi-ethnic locus for T2DM. The strongest association with CAD was detected with SNP rs264 in LPL, which encodes lipoprotein lipase (p = 0.009, OR = 1.96 for allele A). For the cardiometabolic traits analyses, most notable associations were those of FTO with BMI and waist circumference; ABO with height; KCNK16 with diastolic blood pressure; PROX1-AS1, GCKR, and MIR129-LEP with fasting blood glucose; random blood glucose with ZEB2 and THADA; HbA1c levels with TLE1 and FAM99B loci; HDL-cholesterol levels with BRAF; and triglyceride levels with ZEB2. Furthermore, accumulation of risk alleles and polygenic scores of the associated loci was clearly associated with increased risks for all tested diseases and traits in this cohort. The present study highlighted many known genetic loci, which are linked to T2DM and CAD and their associations with major cardiometabolic traits in Arab descendants. We confirmed that some loci are associated with T2DM, CAD, and metabolic traits independently of the ethnic background, with a novel association also detected between height and ABO.