The interaction between oxytocin receptor DNA methylation and genotype has been investigated and whether it is associated with risk of postpartum depression in women without depression in pregnancy.

Postpartum depression (PPD) affects up to 19% of women, negatively impacting maternal and infant health and reductions in plasma oxytocin levels have been associated with PPD and heritability studies have established a genetic contribution.

A team of scientist led by those at the University of Virginia (Charlottesville, VA, USA) carried out a case-control study that included 269 cases with PPD and 276 controls matched on age group, parity, and presence or absence of depressive symptoms in pregnancy as assessed by the Edinburgh Postnatal Depression Scale. Blood was sampled in individuals during pregnancy, between seven and 41 weeks gestation, during normal antenatal care medical visits.

Epigenotyping was performed on DNA extracted from whole blood that was subject to bisulfite treatment. Bisulfite converted DNA was used as a template for polymerase chain reaction (PCR) using a Pyromark PCR kit (Qiagen; Valencia, CA, USA). Pyrosequencing was performed using a suitable primer on a Qiagen Pyromark Q24 using PyroMark Gold Q24 Reagents.

No genetic/epigenetic interactions were found to predict PPD in the total sample. However the scientist identified a significant three-way interaction between the oxytocin receptor OXTR rs53576 genotype, OXTR methylation, and depression in pregnancy in both unadjusted and adjusted models. The authors concluded that depression is especially detrimental in the first year after birth when the mother’s affect and sensitivity to her infant shapes the level of mother–infant emotional engagement, and subsequently impacts the child’s development. The identification of genetic and epigenetic susceptibility to depression in pregnancy may be one key element in a multidisciplinary approach to reduce the development of PPD and hence the adverse sequelae of depression.

C. Sue Carter, PhD, a coauthor of the study said, “The role of the oxytocin system in maternal behavior is well known in rodents. Our work emphasizes its importance in the human maternal condition and places the epigenetic regulation of the oxytocin receptor at the forefront.” The authors hope that the oxytocin receptor marker they have identified will be useful to clinicians in identifying women at risk for postpartum depression. The study was published on July 21, 2015, in the journal Frontiers in Genetics.

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