Overexpression of Androgen Receptors Masculinizes 2D:4D Digit Ratios in Mice.
Level 5 - mechanism / opinion, no new human data
Animal research evaluating genetic androgen receptor overexpression models
PubMed 34625883 · doi:10.1007/s10508-021-02161-y
What was done
The authors compared second-to-fourth digit (2D:4D) ratios across three groups of mice: mice with global androgen receptor (AR) overexpression, mice with neural-specific AR overexpression, and wildtype (WT) littermates. They assessed digit ratio differences between sexes and across genetic groups to evaluate the role of neural versus non-neural AR sensitivity in digit development.
What was found
The abstract reports no exact numerical values, effect sizes, or test statistics. Qualitatively, males showed larger right hind paw 2D:4D digit ratios than females. Mice with global AR overexpression showed increased right hind 2D:4D ratios compared with both WT littermates and neural-specific AR overexpression mice, regardless of sex.
Why it matters
This study provides experimental evidence in a mammalian model that non-neural androgen receptor sensitivity contributes to digit ratio morphology. It supports the mechanistic hypothesis that androgen signaling influences 2D:4D ratios, a marker frequently used in human behavioral endocrinology.
Limits
The abstract provides no sample sizes, effect sizes, or confidence intervals. Findings in rodents may not directly translate to humans, particularly given that the direction of sexual dimorphism in 2D:4D differs between mice and humans (male-typical ratios are larger in mice but smaller in humans). The experiment manipulated receptor expression rather than measuring prenatal hormone levels directly.
Cited by
- supports A sex difference in the 2D:4D digit ratio is present in mice.