Siblings and parents of children with autism: a controlled population-based study.

The siblings and parents of 35 children with infantile autism/autistic disorder were compared with those of children with deficits in attention, motor control and perception (DAMP) and of normal children for reported speech and language problems, reading and spelling problems, social deficits and psychiatric disorders. Children with autism tended more often to be the first and only child and there was some support for genetic stoppage in this group. Learning disorders were equally common among siblings and parents of the autism and normal groups, but less common compared with the DAMP group. Asperger syndrome was more common among first-degree relatives of children with autism compared with normal children. There was a tendency for schizo-affective disorder to be more common among mothers of children with autism. The findings are discussed in the context of a genetic model for the development of autism.