Abstract
Children with high Callous-Unemotional (CU) traits show deficits in recognizing and processing facial expressions. Alterations in emotion recognition have been linked to a higher synaptic concentration of monoaminergic neurotransmitters. The current study investigated the relationship between the MAOA-Low-activity alleles and the ability to recognize and process facial expressions in 97 male children (8-12 years old) diagnosed with disruptive behavior disorder. Participants completed a computerized emotion-recognition task while an eye-tracking system recorded the number (Fixation Count, FC) and length (Fixation Duration, FD) of fixations to the eye region of the emotional stimuli. Children with high CU traits exhibited lower scores in recognition of sadness and anger, and lower FC and FD for sadness and fear than children with low CU traits. Children carrying the MAOA-Low-activity alleles displayed lower FD for sadness, and FD and FC for fear than those carrying the MAOA-High-activity alleles. These genetic effects appeared even stronger in children with CU traits. Moderation analysis revealed that CU traits were associated with lower FC and FD for fear, and lower FD for sadness, probably due to the MAOA-Low-activity alleles. Our findings, although to be replicated, suggest MAOA-Low-activity alleles as potential genetic biomarkers to identify CU children in need of training focused on emotion processing.