The hunt to find genes that cause autism has been a long slog, one hampered by a lack of technology and families willing to be tested.
But those efforts are starting to pay off. On Tuesday, researchers at more than 50 laboratories said they had identified more than 100 genes that are mutated in children with autism, dozens more than were known before.
These are mutations that crop up spontaneously, not ones that parents pass down to their children. At least 30 percent of autism cases are caused by these spontaneous mutations, according to researchers at Cold Spring Harbor Laboratory.
One group of mutations contributes to autism in high-IQ, high-functioning boys, one study found, while another group influences autism in girls and boys with low IQ.
"There's somewhat of a mechanism difference in the genes that are being hit, and the way that gene function is being changed, "says Michael Ronemus, a researcher Cold Spring Harbor Laboratory and an author of one of the studies, which were published Tuesday inNature.
Girls are less likely to get autism than boys, and this study found that the mutations in girls affected genes that play crucial roles during an embryo's early days in the womb. Scientists think that girls are somehow protected against autism, and that it takes a heavy hit like this to cause the disorder in girls.