C2CD4A and type 2 diabetes mellitus: Three Japanese GWAS including ours, have identified the association of the potassium voltage-gated channel KQT-like subfamily member 1 (KCNQ1) locus, ubiquitin-conjugating enzyme E2E 2 (UBE2E2) locus and C2 calcium-dependent domain containing 4A (C2CD4A)-C2CD4B locus with type 2 diabetes [7]–[9].