GDM-related genetic variants are related mainly to the β-cell function, such as CDKAL1_rs7754840, melatonin receptor 1B (MTNR1B)_rs10830963 and rs1387153, cyclin-dependent kinase inhibitor 2A/B (CDKN2A/B)_rs7020996, and HHEX_rs7923837 [16,17,18]. The gene discussed is MTNR1B; the disease is gestational diabetes.