Abstract
Klinefelter's syndrome (47, XXY), a genetical disorder characterized by the presence of an additional X chromosome, neuropsychiatric symptoms are often seen beside of typical physical features. Difficulties in social interactions (i.e., the ability to perceive, understand and express social signals, language and attention) and autism, has been reported for this population. The genetic studies related to pervasive developmental disorder (PDD) and the known predominance of male gender in PDD make us consider that genes on the X chromosome may have a role in the etiology of PDD. In this case report, diagnostic process of a 4 years and 6 months old Klinefelter's syndrome and PDD who had been admitted to our psychiatry unit because of speech delay, insufficiency to obey the instructions, inability to make and sustain friendship with his companions was explained. The aim of this case report was both to review the common autistic findings and to emphasize the importance of etiologic importance of X chromosome abnormalities on autistic findings.
Keywords: Klinefelter's syndrome, pervasive developmental disorder, X chromosome
