A novel rare CUBN variant and three additional genes identified in Europeans with and without diabetes: results from an exome-wide association study of albuminuria.

AIMS/HYPOTHESIS: Identifying rare coding variants associated with albuminuria may open new avenues for preventing chronic kidney disease and end-stage renal disease, which are highly prevalent in individuals with diabetes. Efforts to identify genetic susceptibility variants for albuminuria have so far been limited, with the majority of studies focusing on common variants. METHODS: We performed an exome-wide association study to identify coding variants in a two-stage (discovery and replication) approach. Data from 33,985 individuals of European ancestry (15,872 with and 18,113 without diabetes) and 2605 Greenlanders were included. RESULTS: We identified a rare (minor allele frequency [MAF]: 0.8%) missense (A1690V) variant in CUBN (rs141640975, ß = 0.27, p = 1.3 × 10-11) associated with albuminuria as a continuous measure in the combined European meta-analysis. The presence of each rare allele of the variant was associated with a 6.4% increase in albuminuria. The rare CUBN variant had an effect that was three times stronger in individuals with type 2 diabetes compared with those without (pinteraction = 7.0 × 10-4, ß with diabetes = 0.69, ß without diabetes = 0.20) in the discovery meta-analysis. Gene-aggregate tests based on rare and common variants identified three additional genes associated with albuminuria (HES1, CDC73 and GRM5) after multiple testing correction (pBonferroni < 2.7 × 10-6). CONCLUSIONS/INTERPRETATION: The current study identifies a rare coding variant in the CUBN locus and other potential genes associated with albuminuria in individuals with and without diabetes. These genes have been implicated in renal and cardiovascular dysfunction. The findings provide new insights into the genetic architecture of albuminuria and highlight target genes and pathways for the prevention of diabetes-related kidney disease.

Novel risk genes identified in a genome-wide association study for coronary artery disease in patients with type 1 diabetes.

BACKGROUND: Patients with type 1 diabetes are more at risk of coronary artery disease than the general population. Although evidence points to a genetic risk there have been no study investigating genetic risk factors of coronary artery disease specific to individuals with type 1 diabetes. To identify low frequency and common genetic variations associated with coronary artery disease in populations of individuals with type 1 diabetes. METHODS: A two-stage genome wide association study was conducted. The discovery phase involved the meta-analysis of three genome-wide association cohorts totaling 434 patients with type 1 diabetes and coronary artery disease (cases) and 3123 T1D individuals with no evidence of coronary artery disease (controls). Replication of the top association signals (p < 10-5) was performed in five additional independent cohorts totaling 585 cases and 2612 controls. RESULTS: One locus (rs115829748, located upstream of the MAP1B gene) reached the statistical threshold of 5 × 10-8 for genome-wide significance but did not replicate. Nevertheless, three single nucleotide polymorphisms provided suggestive evidence for association with coronary artery disease in the combined studies: CDK18 rs138760780 (OR = 2.60 95% confidence interval [1.75-3.85], p = 2.02 × 10-6), FAM189A2 rs12344245 (OR = 1.85 [1.41-2.43], p = 8.52 × 10-6) and PKD1 rs116092985 (OR = 1.53 [1.27-1.85], p = 1.01 × 10-5). In addition, our analyses suggested that genetic variations at the ANKS1A, COL4A2 and APOE loci previously found associated with coronary artery disease in the general population could have stronger effects in patients with type 1 diabetes. CONCLUSIONS: This study suggests three novel candidate genes for coronary artery disease in the subgroup of patients affected with type 1 diabetes. The detected associations deserve to be definitively validated in additional epidemiological studies.

Genome-wide association study on coronary artery disease in type 1 diabetes suggests beta-defensin 127 as a risk locus.

AIMS: Diabetes is a known risk factor for coronary artery disease (CAD). There is accumulating evidence that CAD pathogenesis differs for individuals with type 1 diabetes (T1D). However, the genetic background has not been extensively studied. We aimed to discover genetic loci increasing CAD susceptibility, especially in T1D, to examine the function of these discoveries and to study the role of the known risk loci in T1D. METHODS AND RESULTS: We performed the largest genome-wide association study to date for CAD in T1D, comprising 4869 individuals with T1D (cases/controls: 941/3928). Two loci reached genome-wide significance, rs1970112 in CDKN2B-AS1 [odds ratio (OR) = 1.32, P = 1.50 × 10-8], and rs6055069 on DEFB127 promoter (OR = 4.17, P = 2.35 × 10-9), with consistent results in survival analysis. The CDKN2B-AS1 variant replicated (P = 0.04) when adjusted for diabetic kidney disease in three additional T1D cohorts (cases/controls: 434/3123). Furthermore, we explored the function of the lead discoveries with a cardio-phenome-wide analysis. Among the eight suggestive loci (P < 1 × 10-6), rs70962766 near B3GNT2 associated with central blood pressure, rs1344228 near CNTNAP5 with intima media thickness, and rs2112481 on GRAMD2B promoter with serum leucocyte concentration. Finally, we calculated genetic risk scores for individuals with T1D with the known susceptibility loci. General population risk variants were modestly but significantly associated with CAD also in T1D (P = 4.21 × 10-7). CONCLUSION: While general population CAD risk loci had limited effect on the risk in T1D, for the first time, variants at the CDKN2B-AS1 locus were robustly associated with CAD in individuals with T1D. The novel finding on ß-defensin DEFB127 promoter provides a link between diabetes, infection susceptibility, and CAD, although pending on future confirmation.

Association of impaired renal function with venous thrombosis: A genetic risk score approach.

OBJECTIVE: The association between impaired kidney function and venous thrombosis has been previously reported but supportive data are still sparse. We here wish to strengthen this association by investigating, by use of a genetic risk score approach, whether single nucleotide polymorphisms (SNPs) known to decrease the estimated glomerular filtration rate (eGFR), a surrogate marker for renal dysfunction, are associated with increased risk of venous thrombosis. APPROACH AND RESULTS: Fifty-one polymorphisms selected from the literature to robustly associate with eGFR were first tested for association with venous thrombosis in a French case-control collection of 1953 patients and 2338 healthy individuals. This led to the identification of a genetic risk score based on 9 polymorphisms that strongly associated with increased risk (odds ratio (OR)=1.09 [1.06-1.15], p=1.44·10-7). This genetic score association replicated (OR=1.18 [1.11-1.26], p=8.86·10-8) in an independent sample of 1289 patients and 1049 healthy controls part of the Dutch MEGA study. We then categorized the genetic score distribution observed in the combined samples into quintiles. Compared with the lowest quintile, the OR for increased risk of disease associated with the second, third, fourth and fifth quintiles were 1.13 [0.94-1.16], 1.47 [1.22-1.77], 1.52 [1.26-1.82] and 1.70 [1.41-2.05], respectively. CONCLUSIONS: Using a genetic risk score analysis, our study provides new elements supporting the association between impaired renal function and the risk of venous thrombosis.