Replication study for the association of 3 SNP loci identified in a genome-wide association study for diabetic nephropathy in European type 1 diabetes with diabetic nephropathy in Japanese patients with type 2 diabetes

A recent genome-wide association study for diabetic nephropathy in European type 1 diabetes identified 3 candidate loci for diabetic nephropathy. In this study, we examined the association of the 3 single nucleotide polymorphism (SNP) loci with susceptibility to diabetic nephropathy in Japanese subjects with type 2 diabetes. We genotyped 3 SNPs, rs7583877 in AFF3, rs12437854 in the RGMA-MCTP2 locus and rs7588550 in ERBB4, for 2,300 Japanese patients with type 2 diabetes [initial study, 1,055 nephropathy cases with overt proteinuria or with end-stage renal disease (ESRD) and 1,245 control patients with normoalbuminuria]. The association of these SNPs with diabetic nephropathy was examined by using a logistic regression analysis. We observed a significant association of rs7588550 in ERBB4 with diabetic nephropathy in the Japanese patients with type 2 diabetes, although the effect direction was not consistent with that in the European study [p = 0.0126, odds ratio (OR) = 0.79, 95 % confidence interval (CI): 0.65-0.95]. We further examined the association of rs7588550 with diabetic nephropathy in an independent Japanese cohort (596 nephropathy cases and 311 controls) and observed the same trend of the association with the initial study. We did not observe any association of the remaining 2 SNP loci with diabetic nephropathy in the present Japanese sample. The association of SNP loci derived from GWAS in European type 1 diabetes with diabetic nephropathy was not replicated in the Japanese patients with type 2 diabetes, although the ERBB4 locus may have some effect also in Japanese type 2 diabetes.