mutation leads to a single manifestation of sexual development and mimics partial androgen insensitivity syndrome: a case report and literature review.

Objective: To highlight the challenges in diagnosing 46, XY disorder of sex development related to mutation.

Methods: We present an unusual case of a 12-year-old female child came for enlargement of clitoris and initially diagnosed as partial androgen insensitivity syndrome (AIS).

Results: On examination, the patient's vulva was found virilized with 3cm-long clitoris. Her peripheral blood karyotype was 46, XY. The ultrasound showed an empty pelvis and hormone results confirmed hyperandrogenism. Therefore, the partial AIS was suspected, but the following whole exon sequencing indicates a pathological missense mutation in . Further investigation and surgery did not reveal any brain, heart, lung or diaphragm lesions related to MYRF, but only maldeveloped internal genitalia and a persistent urachus. Her serum testosterone dropped to normal after surgical removal of the remaining ipsilateral testis and epididymitis without spermatogenesis as shown by pathology.

Conclusion: Due to the karyotype, hyperandrogenism, empty pelvis but a virilism after puberty, the patient was initially diagnosed as partial AIS. This misleading clinical diagnose will not be verified as the mutation if without the whole exon sequencing, particularly in the absence of obvious brain, heart, lung and diaphragm lesions as in this case.