RESUMEN
Background: NR5A1 [Steroidogenic factor 1 (SF1)] is a nuclear receptor that is essential for the development of gonads and adrenal glands as well as the establishment of steroidogenesis in these organs. The clinical findings of the mutations of NR5A1 gene in 46, XY individuals are variable. Virilization at puberty can be seen in some of the 46, XY children who have a female phenotype and are raised as female.A girl aged 13 years and 10 months old was brought by the family for deepening of her voice. On physical examination, her breast development was Tanner stage 2, axillary hair (+) and pubic hair was Tanner stage 4. She had labioscrotal fusion and 4.4 cm phallus (External Masculinisation Score was 6). Hypergonadotropic hypogonadism, low AMH and high testosterone levels were detected in laboratory tests. Uterus was not visualized in pelvic ultrasonography. Karyotype analysis was reported as 46, XY. Sequence analysis of the NR5A1 gene revealed a novel heterozygote c.1075_1089del (p.Leu359_Leu363del) variant. The patient was raised as a female and oestrogen replacement was started following gonadectomy. Conclusion: It should be kept in mind that virilization may develop at puberty in individuals with 46, XY disorder of sexual development due to NR5A1 mutation.