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5α-Reductase Deficiency: Diagnosis and Treatment

Definition of 5α-Reductase Deficiency

5α-reductase deficiency hinders testosterone conversion into dihydrotestosterone and causes reduced virilization and genital ambiguity in males. The genetic defect affects type 2 of the 5α-reductase (Steers et al., 2001).

Signs and Symptoms of 5α-Reductase Deficiency

• 5α-reductase deficiency affects only males
• The spectrum of symptoms include proximal hypospadias, cryptorchidism, small phallus, ambiguous genitalia, abdominal testes, blind-ending vagina and labioscrotal fusion.
• The onset of puberty results in masculinization (voice, body habitus, genital growth, descensus of the testes) by the rising testosterone (direct effect and conversion by type 1 5α-reductase of the skin).

Diagnostic Workup

• Elevated testosterone and low dihydrotestosterone.
• Genetic analysis of the 5$\alpha$-reductase type 2 gene.

Treatment of 5α-Reductase Deficiency

With early diagnosis, a male gender assignment is reasonable, since with the beginning of puberty, a robust male gender identity will develop. Hypospadias should be corrected early. Substitution of dihydrotestosterone or higher doses of testosterone stimulates genital growth in puberty. Fertility is possible with the help of intrauterine insemination. In missed diagnosis and female gender assignment after birth, surgical corrections should be deferred until puberty (Cohen-Kettenis, 2005).

References

Cohen-Kettenis, P. T. Gender change in 46,XY persons with 5alpha-reductase-2 deficiency and 17beta-hydroxysteroid dehydrogenase-3 deficiency.
Arch Sex Behav, 2005, 34, 399-410

C. Radmayr, G. Bogaert, H. S. Dogan, and Tekg&uuml, “EAU Guidelines: Paediatric Urology,” 2022. [Online]. Available: https://uroweb.org/guidelines/paediatric-urology/.

Steers, W. D. 5alpha-reductase activity in the prostate.
Urology, 2001, 58, 17-24; discussion 24

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