ESR1 and type 2 diabetes mellitus: Gene association studies have so far identified 16 candidate loci involved in PCOS, including genes involved in gonadotropin action (LHCGR and FSHR), metabolism and sexual development (ESR1), insulin signaling and type 2 diabetes (INSR, THADA, HMGA2) or cell proliferation (YAP1 and SUMO1P1) (14).