Background: The large phenotypic spectrum of Disorders of Sex Development are caused by mutations in many different genes, but a large phenotypic spectrum of sexual disturbancies may also be seen with different mutations in the same gene.
Objective and hypotheses: To report on one new mutation in the 5 alfa reductase (SRD5A2) gene, and describe the extremes of the phenotypic spectrum of 5 alfa reductase deficiency presented in two patients.
Method: Patient one was admitted 4 days old due to a micropenis. Parents were non-consanguineous healthy Somalians. Birthweight was 3820 g and birth length was 54 cm at term. Patient two was admitted for suspicion of clitoromegali 6 months old. Parents were non-consanguineous healthy Danes. Birthweight was 1322 g, birthlength was 42 cm at gestational age of 33 weeks. The children had hormonal, chromosomal and genetic analysis. The second child also had an abdominal ultrasound.
Results: Patient one had a penis length of 2.1 cm with urethral orifice at the top of glans penis and retention of testes at the left side, normal testes at the right side and normal scrotum. The second child had a clitoris length of 1.5 cm with an urethral orifice in the normal female position, bilateral gonads in labia majora but a female like vaginal opening. Both children had the male karyotype 46,XY and normal hormonal axis. Testosterone/dihydrotestosterone ratio was 75 (HCG stimulated) in patient one and 15 (unstimulated) in patient two. Abdominal ultrasound of patient two was without Müllarian structures. Genetic analysis of the SRD5A2 gene: Patient one was homozygous for a novel mutation c.682G>A (p.Ala228Thr), patient two was homozygous for c.692A>G (p.His231Arg).
Conclusion: We report a new disease-causing mutation in the SRD5A2 gene, c.682G>A, and underline the very heterogenous phenotype in patients with 5 alfa reductase deficiency, examplified by two patients.
10 - 12 Sep 2016
European Society for Paediatric Endocrinology