Genetic association of single nucleotide polymorphisms in endonuclease G-like 1 gene with type 2 diabetes in a Japanese population

Aims/hypothesis In order to identify type 2 diabetes disease susceptibility gene(s) in a Japanese population, we applied a region-wide case-control association test to the 20.4 Mb region between D3S1293 and D3S2319 on chromosome 3p24.3-22.1, supported by linkage to type 2 diabetes and its related traits in Japanese and multiple populations. Materials and methods We performed a two-stage association test using 1,762 Japanese persons with 485 gene-centric, evenly spaced, common single nucleotide polymorphism (SNP) markers with minor allele frequency > 0.1. For mouse studies, total RNA was extracted from various organs of BKS.Cg-+Lepr(db)/+Lepr(db) and control mice, and from MIN6, NIH3T3 and C2C12 cell lines. Results We detected a landmark SNP375 (A/G) (rs2051211, p=0.000046, odds ratio=1.33, 95% CI 1.16-1.53) in intron 5 of the endonuclease G-like 1 (ENDOGL1) gene. Systematic dense SNPs approach identified a susceptibility linkage disequilibrium (LD) block of 116.5 kb by vertical bar D'vertical bar, an LD units map and a critical region of 2.1 kb by r(2) in ENDOGL1. A haplotype-based association test showed that an at-risk haplotype is associated with disease status (p=0.00001). The expression of ENDOGL1 was rather ubiquitous with relatively abundant expression in the brain and also in a pancreatic islet beta cell line. Mouse Endogl1 expression increased in pancreatic islets of hyperglycaemic BKS.Cg-+Lepr(db)/+Lepr(db) mice compared with that in control mice. Conclusions/interpretation Based on the population genetics, fine mapping of LD block and haplotype analysis, we conclude that ENDOGL1 is a candidate disease-susceptibility gene for type 2 diabetes in a Japanese population. Further analysis in a larger sample size is required to substantiate this conclusion.