SOX9 and disorder of sexual differentiation: Among 46,XY DSD cases with gonadal dysgenesis, about 15% each are due to SRY, NR5A1, and MAP3K1 (mitogen-activated protein kinase kinase kinase 1), and rare cases have been attributed to mutations in other genes such as SOX9 (SRY-box9), NR0B1 (nuclear receptor subfamily 0 group B member 1), or FGFR2 (fibroblast growth factor receptor 2) [17, 18].