Figure 2 – Summary of the molecular events in sex differentiation indicating the genes in which molecular defects cause 46,XY DSD in humans. After testis determination, hormones produced by the male gonad induce the differentiation of internal and external genitalia acting on their specific receptor. The regulation of AMH gene requires cooperative interaction between SOX9 and SF1, WT1, GATA4 and HSP70 at the AMH promoter. Combinatorial expression of DHH, MAMLD1 and SF1 is required for Leydig cell development. SF1 regulates gonadal steroidogenesis. The Leydig cells also produce INSL3, which causes the testes to descend to the scrotum.