School of Psychology, Faculty of Medical Sciences, Newcastle University, UK; Autism Research Centre, Department of Psychiatry, University of Cambridge, UK.
Faculty of Education, University of Cambridge, UK.
Horm Behav. 2020 Nov;126:104867. doi: 10.1016/j.yhbeh.2020.104867. Epub 2020 Oct 6.
The ratio of length between the second and fourth fingers (2D:4D) is commonly used as an indicator of prenatal sex hormone exposure. Several approaches have been used to try to validate the measure, including examining 2D:4D in people with congenital adrenal hyperplasia (CAH), a suite of conditions characterised by elevated adrenal androgen production secondary to defective steroidogenesis. We present a systematic review and meta-analysis that examines the relationship between these two variables. Twelve articles relating to nine CAH cohorts were identified, and 2D:4D comparisons have been made between cases and controls in eight of these cohorts. Altogether, at least one 2D:4D variable has been compared between n = 251 females with CAH and n = 358 unaffected females, and between n = 108 males with CAH and n = 204 unaffected males. A previous meta-analysis (Hönekopp and Watson, 2010) reported lower right hand (R2D:4D) and left hand (L2D:4D) digit ratios in patients with CAH relative to sex-matched controls. Our meta-analysis showed the same pattern, with medium effect sizes for R2D:4D and small effect sizes for L2D:4D. Differences of small magnitude were also observed for M2D:4D, and no significant effects were observed for D. Notably, the only effects that remained statistically significant when stratified by sex were R2D:4D in males and L2D:4D in females, and the average effect size had reduced by 46.70% since the meta-analysis of Hönekopp and Watson (2010). We also found that individual comparisons in this literature were considerably underpowered, and that patterns of sexual dimorphism in 2D:4D were similar in CAH samples as in typically developing populations. Findings are discussed in relation to the prenatal androgen hypothesis as well as alternative explanations.
第二和第四指长度比（2D:4D）通常被用作产前性激素暴露的指标。已经有几种方法试图验证该指标，包括检查先天性肾上腺增生症（CAH）患者的 2D:4D，这是一组由于类固醇生成缺陷导致肾上腺雄激素产生升高的病症。我们进行了一项系统评价和荟萃分析，以检查这两个变量之间的关系。确定了与九项 CAH 队列相关的 12 篇文章，其中八项队列对病例和对照组进行了 2D:4D 比较。总共，至少比较了 n=251 名患有 CAH 的女性和 n=358 名未受影响的女性之间以及 n=108 名患有 CAH 的男性和 n=204 名未受影响的男性之间的至少一个 2D:4D 变量。之前的荟萃分析（Hönekopp 和 Watson，2010）报告称，与性别匹配的对照组相比，CAH 患者的右手（R2D:4D）和左手（L2D:4D）数字比更低。我们的荟萃分析显示了相同的模式，R2D:4D 的效应量中等，L2D:4D 的效应量较小。M2D:4D 也观察到了小幅度的差异，而 D 则没有观察到显著的影响。值得注意的是，当按性别分层时，只有男性的 R2D:4D 和女性的 L2D:4D 仍然具有统计学意义，并且自 Hönekopp 和 Watson（2010）的荟萃分析以来，平均效应大小降低了 46.70%。我们还发现，该文献中的个体比较功率明显不足，并且 CAH 样本中的 2D:4D 性二态模式与典型发育人群相似。研究结果与产前雄激素假说以及替代解释有关。
