Behavioral phenotype of fragile X syndrome: DSM-III-R autistic behavior in male children.

Comparison of 34 fragile X [(fra(X)] male children (age 3-18 years) with 32 IQ- and age-matched, non-fra(X) male control children was conducted using specific DSM-III-R criteria for autism. Statistical analyses supported predictions that fra(X) males show increased dysfunction in peer social play, nonverbal communication (e.g., gaze aversion, gesturing), verbal communication (e.g., rate, volume, word/phrase perseveration), and repetitive motor behaviors (e.g., handflapping, rocking). There was a trend for fra(X) children to show abnormal responsivity to sensory stimuli as well such as oversensitivity to sound and increased mouthing or smelling of objects. The investigation supports the contention that fra(X) males manifest a specific subset of behaviors from the autistic spectrum. Implications for treatment are discussed.