POU5F1 and disorder of sexual differentiation: Mutations in SRY are present in 10-15% of 46,XY DSD patients [10], and these patients have an increased risk of developing GCC, related to the presence of the GBY region (with TSPY as the most likely candidate gene), and the prolonged expression of OCT3/4 (POU5F1) in the germ cells [8,19,20].