Ellis J A, Stebbing M, Harrap S B
Department of Physiology, The University of Melbourne, Parkville, Victoria, Australia.
J Invest Dermatol. 1998 Jun;110(6):849-53. doi: 10.1046/j.1523-1747.1998.00224.x.
Genetic predisposition and androgen dependence are important characteristics of the common patterned loss of scalp hair known as male pattern baldness. The involvement of the 5alpha-reductase enzyme in male pattern baldness has been postulated due to its role in the metabolism of testosterone to dihydrotestosterone. There are two known isozymes of 5alpha-reductase. Type I has been predominantly localized to the skin and scalp. Type II, also present on the scalp, is the target of finasteride, a promising treatment for male pattern baldness. We conducted genetic association studies of the 5alpha-reductase enzyme genes (SRD5A1 on chromosome 5 and SRD5A2 on chromosome 2) using dimorphic intragenic restriction fragment length polymorphisms. From a population survey of 828 healthy families comprising 3000 individuals, we identified 58 young bald men (aged 18-30 y) and 114 older nonbald men (aged 50-70 y) for a case control comparison. No significant differences were found between cases and controls in allele, genotype, or haplotype frequencies for restriction fragment length polymorphisms of either gene. These findings suggest that the genes encoding the two 5alpha-reductase isoenzymes are not associated with male pattern baldness. Finally, no clear inheritance pattern of male pattern baldness was observed. The relatively strong concordance for baldness between fathers and sons in this study was not consistent with a simple Mendelian autosomal dominant inheritance. A polygenic etiology should be considered.
遗传易感性和雄激素依赖性是男性型秃发这种常见头皮毛发脱落模式的重要特征。5α-还原酶在男性型秃发中的作用已被推测，因为它在睾酮代谢为二氢睾酮的过程中发挥作用。已知5α-还原酶有两种同工酶。I型主要定位于皮肤和头皮。II型也存在于头皮上，是非那雄胺的作用靶点，非那雄胺是一种有前景的男性型秃发治疗药物。我们使用双态基因内限制性片段长度多态性对5α-还原酶基因（5号染色体上的SRD5A1和2号染色体上的SRD5A2）进行了遗传关联研究。在对828个健康家庭（共3000人）的人群调查中，我们确定了58名年轻秃发男性（年龄18 - 30岁）和114名老年非秃发男性（年龄50 - 70岁）进行病例对照比较。在任何一个基因的限制性片段长度多态性的等位基因、基因型或单倍型频率方面，病例组和对照组之间均未发现显著差异。这些发现表明，编码两种5α-还原酶同工酶的基因与男性型秃发无关。最后并未观察到男性型秃发明确的遗传模式。本研究中父子间秃发相对较高的一致性与简单的孟德尔常染色体显性遗传不一致。应考虑多基因病因。
