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 here a systematic review 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 (Honekopp & 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 direction of results; however, the effects were only statistically significant for R2D:4D in males and L2D:4D in females (R2D:4D: females, p = 0.072, g = 0.591; males, p = 0.019, g = 0.513; L2D:4D: females, p = 0.020, g = 0.245; males, p = 0.334, g = 0.218), and the average effect size had reduced by 46.70%. We also found no evidence to suggest the right-left difference in 2D:4D (D[R-L]) is associated with prenatal sex hormone exposure.

中文翻译：

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数位比（2D：4D）和先天性肾上腺皮质增生（CAH）：系统文献回顾和荟萃分析

食指与食指之间的长度之比（2D：4D）通常用作产前性激素暴露的指标。已经使用了几种方法来验证该方法，包括检查先天性肾上腺皮质增生（CAH）患者的2D：4D，这是一类特征为继发于类固醇生成不良的肾上腺雄激素产生的疾病。我们在这里提出系统的审查，检查这两个变量之间的关系。确定了涉及9个CAH队列的12篇文章，并且在其中8个队列的病例和对照之间进行了2D：4D比较。总共比较了n = 251位患有CAH的女性和n = 358位未受影响的女性，以及n = 108位CAH的男性和n = 204位未受影响的男性之间的至少一个2D：4D变量。先前的一项荟萃​​分析（Honekopp＆Watson，2010年）报告说，相对于性别匹配的对照，CAH患者的右手手指数（R2D：4D）和左手手指数（L2D：4D）较低。我们的荟萃分析显示了相同的结果方向。然而，男性的R2D：4D和女性的L2D：4D的影响仅具有统计学意义（R2D：4D：女性，p = 0.072，g = 0.591；男性，p = 0.019，g = 0.513； L2D：4D：女性，p = 0.020，g = 0.245；男性，p = 0.334，g = 0.218），平均效果大小减少了46.70％。我们也没有发现证据表明2D：4D（D [RL]）的左右差异与产前性激素暴露有关。然而，男性的R2D：4D和女性的L2D：4D的影响仅具有统计学意义（R2D：4D：女性，p = 0.072，g = 0.591；男性，p = 0.019，g = 0.513； L2D：4D：女性，p = 0.020，g = 0.245；男性，p = 0.334，g = 0.218），平均效果大小减少了46.70％。我们也没有发现证据表明2D：4D（D [RL]）的左右差异与产前性激素暴露有关。但是，对于男性的R2D：4D和女性的L2D：4D，其影响仅具有统计学意义（R2D：4D：女性，p = 0.072，g = 0.591；男性，p = 0.019，g = 0.513； L2D：4D：女性，p = 0.020，g = 0.245；男性，p = 0.334，g = 0.218），平均效果大小减少了46.70％。我们也没有发现证据表明2D：4D（D [RL]）的左右差异与产前性激素暴露有关。