The fragile X marker and autism in perspective.

Recent reports link the fragile X chromosome abnormality to autism, with the association ranging from 0 to 53%, but the diagnostic criteria for autism were unclear in some of the studies. The need for fragile X chromosome studies in larger populations of autistic children and adults was recognized. In this study, chromosome analyses were performed on 85 carefully diagnosed autistic males, yielding a 2.4% incidence of the fragile X abnormality. It is concluded that the incidence of the fragile X chromosome abnormality in autistic individuals is likely the same as that in the mentally retarded male population and therefore does not increase the risk for autism above that of mental retardation itself.