CD38 is associated with communal behavior, partner perceptions, affect and relationship adjustment in romantic relationships.

Given the significance of close relationships for human survival, it is thought that biological mechanisms evolved to support their initiation and maintenance. The neuropeptide oxytocin is one such candidate identified in non-human animal research. We investigated whether variation in CD38, a gene involved in oxytocin secretion and attachment behavior in rodents, predicts romantic relationship dynamics in daily life. Community couples participated in an event-contingent recording (ECR) study in which they reported their social behavior, perception of their partner's behavior, and affect during their interactions with one another over a 20-day period; couples also completed various measures of relationship adjustment. Out of the 111 couples (N = 222 individuals) who provided either ECR and/or relationship adjustment information, we had information on CD38 for 118 individuals. As hypothesized, variation in rs3796863, a single nucleotide polymorphism (SNP) identified in prior work, predicted communal behaviors (e.g., the expression of affection), as well as overall relationship adjustment, such that individuals with the CC (vs. AC/AA) allele reported higher levels of communal behavior across their daily interactions with their romantic partner, as well as higher levels of relationship adjustment. Individuals with the CC (vs. AC/AA) allele of rs3796863 also reported less negative affect and felt insecurity in their interactions with their romantic partner. Notably, we found that variation in the romantic partner's rs3796863 SNP was related to the person's outcomes, independent of the person's rs3796863 genotype. These findings support the role of oxytocin in the interpersonal processes implicated in the maintenance of close relationships.