Heritability and relationship of oxytocin receptor gene variants with social behavior and central oxytocin in colony-reared adult female rhesus macaques

The genetic contributions to sociality are an important research focus for understanding individual variation in social function and risk of social deficits in neurodevelopmental disorders (e.g. autism). The neuropeptide oxytocin (OXT) and its receptor, OXTR, influence social behavior across species. In humans and animals, common variants within the OXTR gene (OXTR) have been associated with varying socio-behavioral traits. However, the reported magnitude of influence of individual variants on complex behavior has been inconsistent. Compared to human studies, non-human primate (NHP) studies in controlled environments have the potential to result in robust effects detectable in relatively small samples. Here we estimate heritability of social behavior and central OXT concentrations in 214 socially-housed adult female rhesus macaques, a species sharing high similarity with humans in genetics, physiology, brain and social complexity. We present a bioinformatically-informed approach for identifying single nucleotide polymorphisms (SNPs) with likely biological relevance. We tested 13 common SNPs in regulatory and coding regions of OXTR for associations with behavior (pro-social, anxiety-like, and aggressive) and OXT concentration in cerebrospinal fluid (CSF). We found moderate rates of heritability for both social behavior and CSF OXT concentrations. No tested SNPs showed significant associations with behaviors or CSF in this sample. Associations between OXT CSF and social behavior were not significant either. SNP effect sizes were generally comparable to those reported in human studies of complex traits. While environmental control and a socio-biological similarity with humans is an advantage of rhesus models for detecting smaller genetic effects, it is insufficient to obviate large sample sizes necessary for appropriate statistical power.