Screening for signs and symptoms of autism spectrum disorders in siblings

Pervasive developmental disorders (PDD) are characterized by comprehensive and qualitative abnormalities affecting three areas of development: reciprocal social interaction, communication, and a repetitive, stereotyped behavioral repertoire, of limited interests. Genetic studies have identified the recurrence of PDD in the same family. The present study aimed to trace the occurrence of signs and symptoms of PDD in the siblings of patients with this diagnosis. The study included 25 subjects from 19 families. Data collection was performed using the Brazilian version of the Autism Screening Questionnaire (ASQ). Two cases of PDD in siblings were confirmed (10.52% of cases): a monozygotic twin brother and the brother of a proband with a diagnosis of Asperger syndrome. Our data indicate higher rates of PDD in siblings than described in the literature (2-6%), close to the findings that suggest a 10% rate of familial recurrence in dizygotic twins. This result provides evidence of possible neurogenetic factors to explain the occurrence of PDD in relatives of the probands assessed and underscores the need to screen not only the child under evaluation, but also their siblings.