Nature 265, 726 - 728 (24 February 1977); doi:10.1038/265726a0

Genetic influences and infantile autism

SUSAN FOLSTEIN & MICHAEL RUTTER

Department of Child and Adolescent Psychiatry, Institute of Psychiatry, London, UK

IN his original description of infantile autism, Kanner suggested an "inborn defect", because symptoms were often present from early infancy. Despite the rarity of a family history of autism and lack of a known increase in parental consanguinity, there are two reasons for suspecting hereditary influences: the 2% rate of autism in siblings is 50 times that of the general population¹, and a family history of speech delay is found in about a quarter of families². Reports of single pairs of twins with autism have not added much to our knowledge of genetic effects because of a bias toward reporting monozygotic (MZ) concordant pairs and because few reports contain both adequate clinical descriptions and evidence of zygosity¹. We therefore undertook a study of a systematically collected sample of 21 pairs of same-sexed twins, one or both of whom had autism as diagnosed by the criteria of Kanner³ and Rutter⁴. The results reported here indicate the importance of hereditary influences in the aetiology of autism.

References

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3.	Kanner, L. Nervous Child 2, 217–250 (1943).
4.	Rutter, M. in Infantile Autism (ed. Churchill, D. W. et al.) (Charles C. Thomas, Springfield, Illinois, 1971).
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