Objective: To review systematically the empirical evidence for the involvement of genetic risk factors in infantile autism.
Method: We aimed at including all relevant papers written in English. We conducted a Medline search in September 2000. In addition we searched the reference lists of related papers.
Results: A relatively small number of reports including family and twin studies, comorbidity, cytogenetic and molecular genetic studies were reviewed.
Conclusion: As well family, twin, cytogenetic and molecular genetic studies supported the importance of genetic risk factors in infantile autism. In most individual cases probably at least a few gene variants simultaneously determine the genetic risk. Presently the most interesting chromosome regions concerning the aetiology of autism are chromosomes 7q31–35, 15q11–13 and 16p13.3 which have been suggested by different lines of genetic research.