WT1 and disorder of sexual differentiation: The intron 9 splice-site mutations with the 3 amino acid residues–lysine (K), threonine (T), and serine (S)–referred to as the +KTS is an important element in gonadal development and the WT1 variant that affects the +KTS/-KTS ratio of the isoforms to <2.0 results in abnormal gonadal development with sexual reversal (female XY-DSD) phenotype and late-onset nephropathy.