Genetics of diabetic kidney disease: A follow-up study in the Arab population of the United Arab Emirates

BACKGROUND

Two genome-wide association studies in European and Japanese populations reported on new loci for diabetic kidney disease (DKD), including FTO. In this study, we have replicated these investigations on a cohort of 410 Type 2 diabetes mellitus (T2DM) patients of Arab origin from the United Arab Emirates (UAE).

METHODS AND RESULTS

The cohort included 145 diabetic patients diagnosed with DKD and 265 diabetics free of the disease. In general, we were able to confirm the association between the FTO locus and DKD, as reported in the Japanese population. Specifically, there were significant associations with two single nucleotide polymorphisms (SNPs), namely rs1421086 (p = .013, OR = 1.52 depending on allele G, 95% CI: 1.09-2.11) and rs17817449 (p = .0088, OR = 1.55 depending on allele C, 95% CI: 1.12-2.14) of the FTO locus. Both SNPs were in linkage disequilibrium with rs56094641, also as reported in the Japanese population. While the alleles of both SNPs, which increase the risk of DKD, were associated with higher Body Mass Index (BMI), their associations with DKD were independent of the BMI effects.

CONCLUSIONS

This study confirms that FTO is a multiethnic locus for DKD which is independent from any influence of BMI and/or obesity.

Genetic Associations With Diabetic Retinopathy and Coronary Artery Disease in Emirati Patients With Type-2 Diabetes Mellitus

Aim: Type 2 Diabetes Mellitus (T2DM) is associated with both microvascular complications such as diabetic retinopathy (DR), and macrovascular complications like coronary artery disease (CAD). Genetic risk factors have a role in the development of these complications. In the present case-control study, we investigated genetic variations associated with DR and CAD in T2DM patients from the United Arab Emirates. Methods: A total of 407 Emirati patients with T2DM were recruited. Categorization of the study population was performed based on the presence or absence of DR and CAD. Seventeen Single Nucleotide Polymorphisms (SNPs), were selected for association analyses through search of publicly available databases, namely GWAS catalog, infinome genome interpretation platform and GWAS Central database. A multivariate logistic regression test was performed to evaluate the association between the 17 SNPs and DR, CAD, or both. To account for multiple testing, significance was set at p < 0.00294 using the Bonferroni correction. Results: The SNPs rs9362054 near the CEP162 gene and rs4462262 near the UBE2D1 gene were associated with DR (OR = 1.66, p = 0.001; OR = 1.37, p = 0.031; respectively), and rs12219125 near the PLXDC2 gene was associated (suggestive) with CAD (OR = 2.26, p = 0.034). Furthermore, rs9362054 near the CEP162 gene was significantly associated with both complications (OR = 2.27, p = 0.0021). The susceptibility genes for CAD (PLXDC2) and DR (UBE2D1) have a role in angiogenesis and neovascularization. Moreover, association between the ciliary gene CEP162 and DR was established in terms of retinal neural processing, confirming previous reports. Conclusions: The present study reports associations of different genetic loci with DR and CAD. We report new associations between CAD and PLXDC2, and DR with UBE2D1 using data from T2DM Emirati patients.

Clinical and genetic associations of renal function and diabetic kidney disease in the United Arab Emirates: a cross-sectional study

OBJECTIVES

Within the Emirati population, risk factors and genetic predisposition to diabetic kidney disease (DKD) have not yet been investigated. The aim of this research was to determine potential clinical, laboratory and reported genetic loci as risk factors for DKD.

RESEARCH DESIGN AND METHODS

Four hundred and ninety unrelated Emirati nationals with type 2 diabetes mellitus (T2DM) were recruited with and without DKD, and clinical and laboratory data were obtained. Following adjustments for possible confounders, a logistic regression model was developed to test the associations of 63 single nucleotide polymorphisms (SNPs) in 43 genetic loci with DKD (145 patients with DKD and 265 without DKD). Linear regression models, adjusted for age and gender, were then used to study the genetic associations of five renal function traits, including 83 SNPs with albumin-to-creatinine ratio, 92 SNPs with vitamin D (25-OH cholecalciferol), 288 SNPs with estimated glomerular filtration rate (eGFR), 363 SNPs with serum creatinine and 73 SNPs with blood urea.

RESULTS

Patients with DKD, as compared with those without the disease, were mostly men (52%vs38% for controls), older (67vs59 years) and had significant rates of hypertension and dyslipidaemia. Furthermore, patients with DKD had T2DM for a longer duration of time (16vs10 years), which in an additive manner was the single factor that significantly contributed to the development of DKD (p=0.02, OR=3.12, 95% CI 1.21 to 8.02). Among the replicated associations of the genetic loci with different renal function traits, the most notable included SHROOM3 with levels of serum creatinine, eGFR and DKD (P_adjusted=0.04, OR=1.46); CASR, GC and CYP2R1 with vitamin D levels; as well as WDR72 with serum creatinine and eGFR levels.

CONCLUSIONS

Associations were found between several genetic loci and risk markers for DKD, which may influence kidney function traits and DKD in a population of Arab ancestry.

Clinical profiles, comorbidities and complications of type 2 diabetes mellitus in patients from United Arab Emirates

OBJECTIVE

To assess clinical profiles of patients with type 2 diabetes in the United Arab Emirates (UAE), including patterns, frequencies, and risk factors of microvascular and macrovascular complications.

RESEARCH DESIGN AND METHODS

Four hundred and ninety patients with type 2 diabetes were enrolled from two major hospitals in Abu Dhabi. The presence of microvascular and macrovascular complications was assessed using logistic regression, and demographic, clinical and laboratory data were collected. Significance was set at p<0.05.

RESULTS

Hypertension (83.40%), obesity (90.49%) and dyslipidemia (93.43%) were common type 2 diabetes comorbidities. Most of the patients had relatively poor glycemic control and presented with multiple complications (83.47% of patients had one or more complication), with frequent renal involvement. The most frequent complication was retinopathy (13.26%). However, the pattern of complications varied based on age, where in patients <65 years, a single pattern presented, usually retinopathy, while multiple complications was typically seen in patients >65 years old. Low estimated glomerular filtration rate in combination with disease duration was the most significant risk factor in the development of a diabetic-associated complication especially for coronary artery disease, whereas age, lipid values and waist circumference were significantly associated with the development of diabetic retinopathy.

CONCLUSIONS

Patients with type 2 diabetes mellitus in the UAE frequently present with comorbidities and complications. Renal disease was found to be the most common comorbidity, while retinopathy was noted as the most common diabetic complication. This emphasizes the need for screening and prevention program toward early, asymptomatic identification of comorbidities and commence treatment, especially for longer disease duration.