*4.4.2 Sex differences*

None of the studies showed sex-dependent effects of OXTR polymorphisms on the ERP components, which was unexpected considering previous findings involving OXTR polymorphism–sex interaction effects on behavior and brain function [65]. For the OXTR rs53576 SNP, there is evidence of sex-dependent effects on the volume of limbic structures, such as the hypothalamus and the amygdala [41], and on functional connectivity of the prefrontal cortex [66, 67]. Furthermore, it has been asserted that sex-dependent differences in the development of brain function and social behavior across different OXTR genotypes are likely linked to the role of sexual hormones regulating OXTR expression [68, 69]. It is likely that, as sample sizes increase, sexdependent effects will be detected.
