Conversational skills of individuals with fragile-X syndrome: a comparison with autism and Down syndrome.

The conversational skills of 18 individuals with fragile-X syndrome (FXS) were compared with those of two other matched groups with autism and Down syndrome. The FXS group used more eliciting forms in conversation than those with Down syndrome, and also used partial self-repetition more often than the other two groups. The Down syndrome group had more speech dysfluencies than those with autism, but not more than those with FXS. The autistic group used more inappropriate phrases. Qualitative analysis of behavioral phenotype may reveal differences in communicative organization among subgroups whose retardation is based on different genotypes. In addition, analysis of verbal strategies during conversation suggests important differences between individuals with FXS and autism.