Background: To explore the reason of children on the 46,XY DSD.
Objective and hypotheses: To analyze the clinical characteristics, diagnosis and management of a case with steroid 5α-reductase type 2 deficiency (SRD5A2) and perform related gene mutation analysis with a view to raising awareness of this disease.
Method: A 2 year old 5 months child came with abnomal vulval shape. Karyotype was analyzed by chromosome cultivation. GnRH and HCG stimulation test were measured. Bone age assessment, MRI and pelvic ultrasonography including uterus and ovary were performed for this patient. The nucleotide sequencing of the SRD5A2, SRY and AR gene was determined by the dideoxy chain termination method. The same gene mutations of SRD5A2 were detected in the patients parents. 2% DHT gel was used for external application.
Results: The karyotypes analysis revealed 46,XY karyotype. The level of AMH was 22.97 ng/ml and Inhibin B was 274.4 pg/ml. The LH and FSH were 0.07 mIU/ml and 0.39 mIU/ml respectively. The peak of LH and FSH were 1.39 mIU/ml and 2.63 mIU/ml respectively 30 min after GnRH stimulation. And the ratio of T to DHT was 51.72. MRI of pelvis revealed uterus and bilateral ovarian-like structures were not visualized. Two ovate isoecho masses which were considered to be testicular tissue with clear boundary were visualized through ultrasound. One with bore diameters of 17.3×8.7 mm was detected in the left labia minora and the other one with bore diameters 15.5×7.4 mm was under the right groin. A negative result from the SRY gene and AR gene mutation analysis of the leukocyte DNA was obtained only from the patient and positive results from SRD5A2 gene mutation were obtained from all members of the family. The length of penis grew up 2 cm after 4 months when treated with 2% DHT gel in its root skin.
Conclusion: The diagonosis of SRD5A2 was mainly based on the elevated ratio of T to DHT. The detection of pathogenic mutation of SRD5A2 was helpful for confirming the case. And it need to be differentiated from CAIS. The external application with 2% DHT gel revealed a good curative effect.
10 - 12 Sep 2016
European Society for Paediatric Endocrinology