Genetics Epidemiology of autism

as late mid-1970s there little evidence of genetic role in autism; evidence genetic epidemiology studies suggests 1 of heritable of psychiatric conditions. first studies of twins estimated heritability more 90%; in other words, genetics explains more 90% of autism cases. when 1 identical twin autistic, other has learning or social disabilities. adult siblings, risk of having 1 or more features of broader autism phenotype might high 30%, higher risk in controls. 10–15% of autism cases have identifiable mendelian (single-gene) condition, chromosome abnormality, or other genetic syndrome, , asd associated several genetic disorders.

since heritability less 100% , symptoms vary markedly among identical twins autism, environmental factors significant cause well. if of risk due gene-environment interaction 90% heritability estimate may high; new twin data , models structural genetic variation needed.

genetic linkage analysis has been inconclusive; many association analyses have had inadequate power. studies have examined more 100 candidate genes; many genes must examined because more third of genes expressed in brain , there few clues on relevant autism.