title: 5 alpha-reductase deficiency in patients with micropenis.
abstract: The enzyme 5 alpha-reductase (5 alpha R), by virtue of its peripheral 5 alpha-reduction of testosterone (T) to dihydrotestosterone (DHT), is believed to play a major role in the differentiation and the subsequent growth of the penis. However, recent studies have reported 5 alpha R deficiency (5 alpha RD) in patients with isolated micropenis and hypothesized that 5 alpha RD is not invariably associated with genital ambiguity. In Egypt, 5 alpha RD has been reported frequently among intersex patients. The aim of this study was to assess the role of 5 alpha RD in the development of micropenis among Egyptian patients with abnormal sexual development. The study included 29 patients who were categorized into three groups (isolated micropenis, 9 patients; microphallus with genital ambiguity, 11 patients; genital ambiguity with normal-sized phallus, 9 patients). Activity of 5 alpha R was assessed by estimating T/DHT ratios in the basal state in pubertal subjects and following human chorionic gonadotropin (HCG) stimulation test in prepubertals. The results showed that the incidence of 5 alpha RD was much higher in cases of ambiguous genitalia with micropenis (5 families out of 10, 50%) than in those with isolated microphallus (1/9, 11.1%) or those with ambiguous genitalia and normal-sized phallus (1/8, 12.5%). In conclusion, the study showed that isolated micropenis is a heterogeneous disorder and that 5 alpha RD, despite its relative prevalence in Egypt, has a minimal role in the aetiology. On the other hand, 5 alpha RD seems to correlate with penile length in intersex cases.
authors.affiliation: Human Genetics Department, National Research Center, Dokki, Giza, Egypt.
authors.forename: Y Z
authors.initials: YZ
authors.lastname: Gad
authors.forename: H
authors.initials: H
authors.lastname: Nasr
authors.forename: I
authors.initials: I
authors.lastname: Mazen
authors.forename: N
authors.initials: N
authors.lastname: Salah
authors.forename: R
authors.initials: R
authors.lastname: el-Ridi
mesh_terms: D013741:3-Oxo-5-alpha-Steroid 4-Dehydrogenase / Q000172:deficiency*; D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D006062:Gonadotropins / Q000032:analysis; D006801:Humans; D007223:Infant; D008297:Male; D010413:Penis / Q000502:physiology*; D013739:Testosterone / Q000032:analysis
chemical_list: D006062:Gonadotropins; D013739:Testosterone; D013741:3-Oxo-5-alpha-Steroid 4-Dehydrogenase