What is the role of deficiency of 5-alpha reductase in the etiology of microphallus?

Updated: Nov 30, 2020
  • Author: Karen S Vogt, MD; Chief Editor: Sasigarn A Bowden, MD  more...
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5-alpha reductase peripherally converts testosterone to the more potent DHT, which is necessary for virilization of the male external genitalia. The genitalia in most children with this autosomal recessive condition are usually more ambiguous, with varying degrees of incomplete labioscrotal fusion and hypospadias. The hallmark biochemical abnormality is an elevated testosterone-to-DHT ratio (usually >30:1) after hCG stimulation if prepubertal. These individuals also undergo profound virilization at puberty. Genetic testing for SRD5A2 gene mutations is commercially available. [15, 25, 26]

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