It has not yet been definitely established what causes Asperger syndrome. A genetic contribution is clearly important in many cases. Some cases have been linked to damage or developmental abnormalities in the brain arising either in foetal life or in the first years after birth. It is possible that some instances of the syndrome are attributable to the combination of genetic and brain damaging events. Psychosocial factors in themselves appear to contribute little in terms of causing the syndrome, but may be very important from the point of view of outcome.

Genes

At least half of all children, adolescents and adults with Asperger syndrome have a close relative – parent or sibling – with similar, albeit not necessarily identical, problems. It has also been well established that some individuals with Asperger syndrome have children with similar, indeed sometimes almost identical, difficulties. However, it is far from clear how large a proportion of all those with Asperger syndrome are liable to have children with similar functional impairments.

Asperger syndrome is considered an autism spectrum disorder. That autism itself is a strongly genetic condition has been shown convincingly by several twin and family studies. Those studies have also demonstrated that in many cases it is not ‘autism per se’ that is inherited, but rather a broader range of autism spectrum problems (‘autistic traits’). Family studies have shown clearly that autism and Asperger syndrome often occur within the same larger family tree. Full genome screen studies have been performed in autism.