The author described a male patient, age 13 years and 5 months, with behavioral profile meeting the criteria of the autistic syndrome by the DSM-III-R (APA, 1989) and DSM-IV (APA, 1995). After clinical and laboratory examinations, it was found that he had an abnormal karyotype, 46 XY, R(22). The need for clinical and laboratory case studies of autism is of great importance to develop data for defining an etiological basis for diagnosis.