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5α-Reductase Deficiency

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 hypospadia, 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.
• Low or absent 5α-reductase activity of cultured genital skin fibroblasts.

Treatment of 5α-Reductase Deficiency

With early diagnosis, a male gender assignment is reasonable, since with the beginning of puberty, a strong male gender identity will develop. Hypospadia should be corrected early. Substitution of dihydrotestosterone or higher doses of testosterone stimulate the 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

  Deutsche Version: 5α-Reduktase Mangel