Three independent studies released on Wednesday showed that certain gene mutations could increase the chances of developing autism, and also that the risk increases with the age of the father, according to The New York Times.
The findings were published in the journal Nature.
CBS News said the mutations that were found in the parts of genes that code for proteins played a significant role in the development of autism. The first study looked at 677 individuals from 209 families, each with one child who was diagnosed with autism.
It found 126 "de novo" mutations, meaning that they came from neither parent, that could possibly contribute to autism. The mutations were four times as likely to happen in sperm than in egg cells, and the older the father, the more likely his sperm contained the mutations.
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In another of the studies, researchers compared siblings with and without autism, finding that the sibling with autism had two different mutations of the gene SCN2A, according to ABC News.
The third study, led by Harvard Medical School and MIT's Broad Institute found that the chance that mutations played a role in the development of autism was modest, but still provided important evidence of autism risk factors, according to CBS News.
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Dr. Thomas Insel, the director of the National Institute of Mental Health (which funded one of the studies), said, "These results confirm that it's not the size of the genetic anomaly that confers risk, but its location," according to Reuters.
The gene mutations are extremely rare, said The Times, and account for a tiny fraction of autism cases, making the search for therapies more difficult.
Bloomberg said the mutations may help scientists classify different types of the developmental disorder and tailor treatments according to their DNA profiles.
The CDC recently revealed that the rates of autism in the US had increased by 78 percent in the past decade.
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