No effects of androgen receptor gene CAG and GGC repeat polymorphisms on digit ratio (2D:4D): Meta-analysis

TL;DR

This meta-analysis found no evidence linking androgen receptor gene CAG and GGC repeat polymorphisms to digit ratio (2D:4D), challenging its validity as a marker of prenatal androgen exposure.

Contribution

It provides a comprehensive meta-analytical review showing no association between specific androgen receptor gene variants and digit ratio, contradicting earlier smaller studies.

Findings

No significant association between CAG repeats and 2D:4D

No significant association between GGC repeats and 2D:4D

Meta-analysis undermines 2D:4D as a prenatal testosterone marker

Abstract

Objectives: A series of meta-analyses assessed whether differentially efficacious variants (CAG and GGC repeat-length polymorphisms) of the human androgen receptor gene are associated with digit ratio (2D:4D), a widely investigated putative pointer to prenatal androgen action. Methods: Extensive literature search strategies identified a maximum of 16 samples (total N = 2157) eligible for meta-analysis. Results: In contrast to a small-sample (N = 50) initial report, widely cited affirmatively in the literature, meta-analysis of the entire retrievable evidence base did not support associations between androgen receptor gene efficacy and 2D:4D. Conclusions: These meta-analytical nil findings, along with several further suggestive strands of evidence consistent with these, undermine one validity claim for 2D:4D as a retrospective pointer to prenatal testosterone action.