New research on hundreds of families affected by autism is offering the strongest evidence yet that gene mutations — which are more likely among older fathers — increase a child’s odds of the developmental disability.

The findings come from three studies published Wednesday in the journal Nature looking at the genetic makeup of parents and their children with autism in more than 500 families. In each case, the parents displayed no signs of autism but had at least one child with the disorder.

Researchers behind the studies identified spontaneous genetic mutations believed to be responsible for some cases of autism and said they expect more to be pinpointed.

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While most people have similar glitches in their DNA, the location of gene mutations near areas that affect brain development may increase the chance of autism, the scientists said.

“We now have a good sense of the large number of genes involved in autism and have discovered about 10 percent of them,” said Joseph Buxbaum of the Mount Sinai School of Medicine who was involved in one of the studies. “We need to study many more parents and their affected children if we are to uncover the genes important in ASD. As these genes are further characterized, this will lead to earlier diagnosis and novel drug development.”

Significantly, researchers in one of the studies found that the gene mutations contributing to autism were four times more likely to originate from a child’s father as compared to their mother. Moreover, the likelihood of the mutations being present appeared to increase with the father’s age.