In the field of sex development, digenic inheritance has recently been suggested in a 46,XY DSD patient with gonadal dysgenesis (NR5A1 and MAP3K1 variants) (Mazen et al., 2016); in a family with 46,XY DSD males (NR5A1 variants) and 46,XX POF females (NR5A1 and TBX2) (Werner et al., 2017); as well as in a DSD patient with ambiguous genitalia, micropenis, and inguinal testes (SEMA3A and AKR1C4) (Fan et al., 2017). The gene discussed is MAP3K1; the disease is disorder of sexual differentiation.