Klinefelter syndrome (KS) is the most common sex-chromosome aneuploidy (47,XXY), affecting 1 in 500 male participants. The phenotype of male participants with KS includes both physical features, such as tall stature and testicular insufficiency, and behavioral alterations, including difficulties in social functioning, anxiety, and depression. Studies examining underlying neural alterations associated with the behavioral phenotype, however, are sparse. We aimed to address this gap in knowledge using functional magnetic resonance imaging in conjunction with an emotion processing paradigm. Functional magnetic resonance imaging was conducted on 38 children and adolescents with KS ( Mage = 12.85, SD = 2.45) and 47 typical developing (control) boys ( Mage = 12.04, SD = 1.82) as they completed a facial emotion processing task. Group differences in activation occurring during the processing of angry versus neutral faces were examined while controlling for age. The results indicated that relative to typically developing boys, boys with KS exhibited anomalous increases in activation of frontal, temporal, and occipital cortices. Within the KS group, secondary analyses indicated that greater activation in these regions was associated with more internalizing symptoms (e.g., anxiety, depression, withdrawn behaviors) and greater social impairments (e.g., social cognition, social communication, social motivation, social communication and interaction, functional communication). The findings from this study indicate a possible neural correlation for difficulties in social and emotional function in KS and add to a growing body of research aimed at increasing our understanding of neural biomarkers in this condition. Future studies that examine the influence of testosterone-replacement therapy on these differences are warranted.
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