HHEX and type 2 diabetes mellitus: Internationally, GWAS have successfully identified over 100 susceptibility genes for T2DM, such as adenylyl cyclase 5 (ADCY5), hematopoietically expressed homeobox (Hhex), Potassium voltage-gated channel subfamily Q member 1 (KCNQ1), and cyclin dependent kinase inhibitor 2A (CDKN2A).