Overlap With the Autism Spectrum in Young Children With Williams Syndrome

Objective: The sociocommunicative abnormalities of young children with Williams syndrome (WS) with limited language were compared with those of children with clinical diagnoses of autism, Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS), or nonspectrum developmental disability. Method: Participants were 30 children with WS and individually matched groups of participants with autism (n = 28), PDD-NOS (n = 17), and mixed etiology nonspectrum developmental disabilities (n = 16). The autism, PDD-NOS, and mixed etiology groups were matched individually to the children with WS for age, sex, and developmental level. All participants were administered the Autism Diagnostic Observation Schedule Module 1 and the Mullen Scales of Early Learning. Results: As a group, children with WS with limited language showed fewer sociocommunicative abnormalities than children with autism, about the same level at children with PDD-NOS, and more abnormalities in reciprocity social interaction than participants in the mixed etiology group. Examination of the subgroup of participants with WS matched and compared with children with PDD-NOS indicated that half of the children showed fewer abnormalities than their individual matches with PDD-NOS, whereas half of the children with WS showed more abnormalities than their matches with PDD-NOS. Conclusion: Sociocommunicative difficulties are present for many children with WS and overlap with the autism spectrum. The results of this investigation suggest that these abnormalities are not accounted for by developmental delay alone, and care should be taken to avoid diagnostic overshadowing in young children with WS.