These findings are in line with previously observed biological differences, such as lower plasma oxytocin levels in GG homozygotes [81] and results reported by Costa et al. [40] in an Italian sample, which showed a positive association between the GG genotype and unipolar depression, and seem to indicate that this target gene has a higher relevance in the Caucasian population than in the Asian population. The gene discussed is OXT; the disease is major depressive disorder.