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.