Genetic Variants in Oxytocinergic System Genes and Their Association with Postpartum Depression Susceptibility

One of the most frequent forms of maternal morbidity following childbirth is postpartum depression. Postpartum depression (PPD), a disabling condition as a major public health concern, has a significant negative impact on the child's emotional, mental as well as intellectual development if left undiagnosed and untreated, which can later have long-term complications. The oxytocin system is an excellent candidate gene system in the maternal context. Differences in vulnerability of mothers for the onset of postpartum psychiatric disorders could be influenced by individual differences in the genetic profile of each one. In this original research, we aimed to explore if there are any possible contributions of genetic variation on both the oxytocin receptor gene (OXTR) and the oxytocin gene (OXT) to the occurrence of postpartum depression, aiming to provide the latest evidence and determine which genetic polymorphisms significantly create a susceptibility for this condition. A total of 100 mothers were preliminarily genotyped before they completed the Edinburgh Postnatal Depression Scale Questionnaire (EPDS) at 6 weeks postpartum. DNA was extracted from peripheral blood samples of the participants (N = 100) and evaluated for the oxytocin gene (OXT_rs2740210; OXT_rs4813627) and oxytocin receptor gene (OXTR_ rs237885) single nucleotide polymorphisms. The results highlighted a significant interaction between the oxytocin OXT_rs2740210 genotype and maternal postpartum depression in mothers with the CC genotype but not in those with AA/AC genotypes. This reveals that an interaction of vulnerable genotypes (CC genotype of OXT_rs2740210, C allele in genotype of OXT_rs2740210, G allele in genotype of OXT_rs4813627) with an environmental burden or other risk factors would predispose the mothers to develop postpartum depression. We found no significant association between the interaction effect of the oxytocin receptor gene OXTR_rs237885 genotype depending on the occurrence of maternal postpartum depression. These findings prove the implication of the oxytocinergic system gene variants in vulnerability for postpartum depression and indicate the need for future studies adopting a multilevel approach in order to increase understanding.