Although Klinefelter syndrome (47,XXY) has been associated with psychosocial difficulties, knowledge of the social behavioral phenotype is limited. We examined specific social abilities and autism traits in Klinefelter syndrome. Scores of 31 XXY men on the Scale for Interpersonal Behavior and the Autism Spectrum Questionnaire were compared to 24 and 20 control men respectively. XXY men reported increased distress during social interactions and less engagement in specific social behaviors. In the XXY group, levels of autism traits were significantly higher across all dimensions of the autism phenotype. These findings call for a clinical investigation of vulnerability to autism in Klinefelter syndrome. Klinefelter syndrome might serve as a model for studying a role of the X chromosome in social behavioral dysfunction and autism-like behavior.

Klinefelter's syndrome, characterised by a 47,XXY chromosomal pattern, has largely been associated with physical abnormalities. Here, we report high levels of schizophrenia-spectrum pathology in 32 men with this syndrome in comparison with 26 healthy controls. This may have implications for treatment of have implications for treatment of Klinefelter's syndrome and suggests that the X chromosome may be involved in the aetiology of schizophrenia.

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