OXTR and major depressive disorder: However, contrary to these findings, for G allele homozygotes, other studies have also revealed: (i) greater adult emotion dysregulation [39], which has been implicated in depression, in individuals who experienced severe childhood maltreatment, (ii) a positive association with unipolar depression in an Italian sample [40] and (iii) a positive correlation between childhood maltreatment and the severity of depression symptoms, indicating a possible gene–environment interaction between early childhood experience and OXTR genotypes [41].