Scientists have long known that people with autism have brains that work differently -- their brain activity doesn't follow the usual pathways for speech, thought or social interaction. Still, the lingering question has always been: why?
New research published in the online medical journal Nature today offers the best evidence yet that a major part of the answer is genetics.
For the first time, scientists have identified specific genetic mutations that lead to specific abnormalities in how brain cells communicate and carry messages in the brains of those with autism.
"The genes that were discovered appear to be involved in the development of the frontal lobe of the brain ... that is, involved in complex behavior such as social behavior and also abstract thought," said Dr. Geri Dawson, chief officer of Autism Speaks and co-author of the study. "So it helps us understand why people with autism have difficulty in the area of social interaction -- and also why they have a tendency to be so concrete and literal in their interpretation."
Autism, a neurodevelopmental disorder that impairs social interaction, communication and behavior, tends to run in families. According to the National Institutes of Health, families with one autistic child have a one in five chance of having a second child with the disorder.
Scientists have long suspected a genetic underpinning for autism, but have had difficulty finding the link. Previous studies in families with identical twins have found that when one twin has autism, the odds are relatively strong that the other will too.
But the latest research -- one of the largest studies to date -- goes beyond twin studies, using cutting edge technology to examine and compare the DNA from more than 12,000 individuals affected by autism. Scientists pooled data together to gather a sample large enough.
Erica Romano of Brooklyn, N.Y., volunteered her family for the study. As a mother of two sons with autism, Romano has strong convictions that autism involves genes.
"I have a third cousin who has Aspergers and a first cousin who has PDD/autism," she told ABC News. "I'm really hoping that this study sheds some light on the genetic factor."
By comparing the DNA of those with and without autism, researchers were able to identify several genes related to autism. Scientists say that autism, a complex disorder, could be caused by as many as 50 genes.
The findings point researchers in the right direction toward developing drugs to treat the disorder.
"What we're discovering in this study is that these genes appear to be affecting similar biochemical pathways in the brain, and so then, if we can develop drugs that can help to repair or restore that pathway, this eventually could be extremely helpful as a treatment," said Dawson.
For parents like Romano, the studies hold promise to change the destiny of those with autism by finding a cure. While it won't come overnight, this research opens the door to understanding the genetic mysteries of autism.
"There are so many steps down the road before we can develop these medications," Dawson said. "But this is the first step -- and without this step, we would never get there."