Fifty males with the fragile X [fra(X)] syndrome, which we consider synonymous with the Martin-Bell syndrome, were identified by a chromosome analysis of patients with developmental delays or mental retardation and family studies of known fra(X) pedigrees. These males were evaluated for autism using three criteria: (1) the DSM III diagnostic criteria for Infanti, Autism; 2) the Autism Behavior Checklist (ABC); and 3) the Diagnostic Checklist for Behavior Disturbed Children, Form E2. Sixteen percent of patients fulfilled all of the DSM III criteria for Infantile Autism and an additional 30% fulfilled criteria for Infantile Autism Residual State. Thirty-one percent of patients had autism using the ABC checklist but none of the patients fit the classical Kanner syndrome as described by the E2 questionnaire. Some autistic traits were seen in almost all of the 50 fra(X) patients, including eye avoidance in 90%, handflapping, handbiting or handstereotypies in 88%, and language delays with language peculiarities, usually echolalic speech, in 96%. A pervasive lack of responsiveness was seen in 18% at their present age and in 44% in earlier childhood only.
Autistic symptoms are common in the fra(X) syndrome. Therefore, any patient with developmental delays and autism or autistic manifestations should have a chromosomal analysis, including fra(X) examination.