INCOMPLETE MASCULINIZATION DUE TO A DEFICIENCY OF 17β‐HYDROXYSTEROID DEHYDROGENASE: COMPARISON OF PREPUBERTAL AND PERIPUBERTAL SIBLINGS

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Abstract
SUMMARY: Incomplete masculinization due to a deficiency of 17β‐hydroxysteroid dehydrogenase (17β‐HSD) was investigated in siblings aged 4 years (Case 1) and 12 years (Case 2). Diagnosis was based on increased ratios of androstenedione (A) to testosterone (T) in blood, and impaired reduction of A to T by 17β‐HSD in vitro in the testes. Impairment was total in Case 2 but partial in Case 1. Case 2 also showed deficient conversion of dehydroepiandrosterone (DHA) to androstenediol and of oestrone to oestradiol by 17β‐HSD which were normal in Case 1. Oxidation of T to A by 17β‐HSD and conversion of 17α‐hydroxyprogesterone to A by 17,20 desmolase were normal in the testes of both siblings. 3β‐HSD conversion of DHA to A was normal in Case 1, but markedly increased in Case 2. In contrast to testicular findings, 17β‐HSD reduction of A to T in genital skin fibroblasts from Case 2 was normal and diagnosis would not have been possible from studies of measurements of this enzyme in skin. The severity of the testicular 17β‐HSD deficiency in the peripubertal compared with the prepubertal sibling suggests either considerable intra‐familial variation in the extent of the enzyme defect or that puberty may aggravate this disorder. The normal reductive action of 17β‐HSD in skin, despite impaired action in testes, suggests involvement of more than one iso‐enzyme.

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