CD38 genetic variation linked to enhanced mPFC responses to smiles in 7-month-old infants

The oxytocin system is a crucial neurobiological pathway regulating social behaviors and emotional bonding. Dysregulation in this system is implicated in various neurodevelopmental disorders characterized by social deficits, such as autism spectrum disorder. While oxytocin's role in adult social cognition is well-established, understanding its influence on early social brain development, particularly how genetic variations impact the processing of affiliative cues like smiles, remains a critical gap. This study investigates how specific genetic differences within the oxytocin pathway contribute to individual variability in infant social brain function.

Researchers investigated the link between genetic variation in the oxytocin system and medial prefrontal cortex (mPFC) responses to social stimuli in human infants. The study focused on 7-month-old infants, examining their mPFC activity while viewing different facial expressions. Specifically, they analyzed genetic variation in CD38 (rs3796863), a gene previously associated with oxytocin release. The primary endpoint was the differential mPFC response to smiles compared to angry or fearful faces, with genetic genotype serving as the independent variable.

Genetic variation in CD38 (rs3796863), a single nucleotide polymorphism linked to oxytocin release, was significantly associated with differential brain activity. Infants carrying specific CD38 genotypes exhibited enhanced mPFC responses when viewing smiles. This heightened response was specific to positive social cues, as no such association was observed when infants viewed angry or fearful faces. This finding suggests a genotype-dependent modulation of the neural processing of affiliative signals. The study provides novel evidence that early-emerging differences in social brain function are influenced by oxytocin-related genetic variability. This supports the view that neurogenetic mechanisms play a role in shaping the processing of social cues from early human development. The specific genotype associated with enhanced responses was not detailed in the abstract, but the presence of this genetic variation was the key determinant. This indicates a direct link between genetic predisposition in the oxytocin system and how infants' brains process positive social interactions.

Genetic variation in CD38 (rs3796863) was associated with enhanced mPFC responses when 7-month-old infants viewed smiles, but not angry or fearful faces.