Results from a large battery of experimental socio-cognitive tasks and standardized assessments revealed a partial WS socio-cognitive profile in the girl, contrasting with a more autistic-like profile in the boy, suggesting that deletion of the telomeric genes alone (including GTF2I) cannot fully account for the hypersociability typical of individuals with WS, and that genetic contributions to phenotypic outcomes involve complex interactions between genes. Here, GTF2I is linked to Werner syndrome.