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Disorders of Sex Development — RACP Paediatrics MCQ

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HardEndocrinologyDisorders of Sex DevelopmentRACP Paediatrics

A newborn is found to have ambiguous genitalia with bilateral palpable gonads in the inguinal canal, a micropenis, and perineal hypospadias. Karyotype is 46,XY. Which condition is the most likely cause?

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Correct answer: E — 5-alpha reductase deficiency

In a 46,XY infant with ambiguous genitalia and bilateral palpable testes, 5-alpha reductase deficiency is a key consideration. This enzyme converts testosterone to dihydrotestosterone (DHT), which is necessary for external masculinisation. Affected individuals have female or ambiguous external genitalia at birth with virilisation at puberty. Complete androgen insensitivity presents as phenotypically female with inguinal testes.

Reference: RCH Melbourne – 2024 – Clinical Practice Guidelines: Disorders of Sex Development