Fragile X syndrome, DSM-III-R, and autism.

Although reports of autistic behavior in fragile X males have been published for 8 years, there is little information about specific behaviors shown by fragile X males that are suggestive of the diagnosis of autism. The new diagnostic criteria for autistic disorder contained in the DSM-III-R provided the opportunity for more closely investigating the topography of autistic behavior in 17 fragile X males and the effects of age and IQ on its occurrence. The criteria most frequently met by these subjects were related to deficits in social interaction with peers, abnormalities in verbal and nonverbal communication, stereotypic motor behavior, and unusual responses to sensory stimuli. Fragile X subjects did not frequently show abnormalities in attachment behaviors and reciprocal interaction with caregivers. There were no discernable age or IQ effects. The importance and implications of these findings are discussed and the need for greater exploration of autism "subtypes" is emphasized.