A total of 19 genes that may be candidate genetic markers for GDM were mapped through functional mapping, in which twelve (APC, BRCA1, CLOCK, GRIN3B, GSK3B, NR3C1, PRDM16, SALL3, SYCP2, TMEM259, TPH1, and TPH2) were directly mapped by variants genotyped in our study. The gene discussed is TMEM259; the disease is gestational diabetes.