Gad Y Z, Nasr H, Mazen I, Salah N, el-Ridi R
Human Genetics Department, National Research Center, Dokki, Giza, Egypt.
J Inherit Metab Dis. 1997 Mar;20(1):95-101. doi: 10.1023/a:1005326027087.
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.
5α-还原酶（5αR）可将外周的睾酮（T）5α-还原为二氢睾酮（DHT），据信该酶在阴茎的分化及后续生长过程中发挥着主要作用。然而，近期研究报道了孤立性小阴茎患者存在5αR缺乏（5αRD）的情况，并推测5αRD并非总是与生殖器模糊相关。在埃及，5αRD在两性畸形患者中屡有报道。本研究旨在评估5αRD在埃及性发育异常患者小阴茎发育中的作用。该研究纳入了29例患者，分为三组（孤立性小阴茎，9例；伴有生殖器模糊的小阴茎，11例；伴有正常大小阴茎的生殖器模糊，9例）。通过估算青春期受试者基础状态下的T/DHT比值以及青春期前受试者人绒毛膜促性腺激素（HCG）刺激试验后的T/DHT比值来评估5αR的活性。结果显示，伴有小阴茎的生殖器模糊病例中5αRD的发生率（10例中有5例，50%）远高于孤立性小阴茎病例（1/9，11.1%）或伴有正常大小阴茎的生殖器模糊病例（1/8，12.5%）。总之，该研究表明孤立性小阴茎是一种异质性疾病，5αRD尽管在埃及相对常见，但在病因学中作用极小。另一方面，在两性畸形病例中，5αRD似乎与阴茎长度相关。
