About 81 percent of autism risk comes from inherited genetic factors, according to an analysis of more than 2 million children from five countries, published [July 17] in JAMA Psychiatry.
The study is the largest yet to estimate the heritability of autism risk in a multinational population. The findings are consistent with results from a large 2017 study of twin and non-twin sibling pairs in Sweden that suggested about 83 percent of autism risk is inherited. A third study — also in Sweden and also in twins — reported in 2010 that these factors contribute to about 80 percent of autism risk.
The new study improves upon the previous work by analyzing multiple generations of families from several countries.
The researchers also examined other factors tied to autism. For instance, an estimated 18.1 percent of autism risk arises from environmental factors that are not shared among family members. This includes noninherited, or de novo, mutations, [researcher Joseph] Buxbaum says. The team also looked at factors that are shared among family members, such as the home environment, but found that they generally do not contribute to autism risk.
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