A sweeping study of hundreds of families with autism has found that spontaneous mutations can occur in a parent's sperm or egg cells that increase a child's risk for autism, and fathers are four times more likely than mothers to pass these mutations to their children, researchers said Wednesday.

The results of three studies, published in the journal Nature, suggest that mutations in parts of genes that code for proteins - called the exome - play a significant role in autism.

And while these genetic mistakes can occur across the genetic code, and many are harmless, they can cause big problems when they occur in parts of the genome needed for brain development. One of the three teams found these glitches may result in a five to 20 times higher risk of developing autism.

In the United States, an estimated 1 in 88 children have autism, according to the latest figures from the U.S. Centers for Disease Control and Prevention, and while scientists believe genetics account for 80 to 90 percent of the risk for developing autism, most cases of autism cannot be traced to a known inherited cause.

--REUTERS

Read more from the journal Nature.