Scientists have identified a genetic pattern common to people with autism that is linked to the way messages are sent in the brain.
Researchers at Oxford said the knowledge could help them understand the role that genetics plays in autism.
Doctors can only identify the exact genetic cause of autism in about one in five cases, but it is known genes play an important role in the development of autism spectrum disorders.
A total of 181 autism patients who either had additional copies of some genes, or fewer copies, than those without autism were studied.
The researchers found that, in about half the patients, the affected genes worked together as part of a biological network involved in the way information passes between brain cells.
Dr Caleb Webber said: "Think of a pipe that carries water. At some points along the pipe, there are genes that act as taps to let more water into the pipe.
"At other points, genes act as holes to let some of the water out. We found that, in individuals with autism, the mutations in all these different types of genes act in the same way to affect water flow.
"This indicates the 'tap' genes are duplicated in some individuals with autism which increases flow into the pipe, while in other individuals with autism the 'hole' genes are deleted, which decreases the amount of water leaving the pipe.
"Both of these events cause the same thing – too much water flowing through the pipe."