Jan 7, 2011
7:28 PM ET
By Rachael Rettner, MyHealthNewsDaily Staff Writer
"People are going to manifest the disorder in different ways, and that could be because there are different sets of genes, [or] different sets of environmental factors," that contribute to how the disorder presents itself, said Alycia Halladay, director of research for environmental sciences for Autism Speaks, an autism advocacy organization that funds autism research.
Here are #1-2 findings and ideas from scientists about what might really cause this mysterious condition.
There is strong evidence that changes in our genes contribute to autism. For one thing, the disorder is highly heritable. Families that have one child with autism have a 1 in 20 chance of having a second child with autism, according to the National Institutes of Health. This is a higher risk than in the general population. And twin studies have found that if one twin has autism, the other twin as a 90 percent chance of having the disorder.
Research has also shown that the genetic changes that contribute to autism don't have to be inherited — they may also arise spontaneously.
In total, scientists have identified about 20 genes that may be involved in autism spectrum disorder, Halladay said. While these genes are located all over the human genome, they share a common theme, she said. Many have a role in brain development, brain growth and the way brain cells communicate.
For example, a recent study found that children with a genetic mutation on chromosome 17 were 14 times more likely to develop autism than those without the mutation.
Exposure to pesticides has also been linked to autism. Some studies have found that pesticides may interfere with genes involved in the central nervous system, said Dr. Alice Mao, an associate professor of psychiatry at Baylor College of Medicine in Houston.
Scientists think that chemicals in pesticides may adversely affect those who are genetically predisposed to autism, leading them to develop the full-blown disorder, Mao said.
"Maybe they were born with a vulnerability to autism, but then exposure to the pesticides might have cause the presentation of autism," Mao told MyHealthNewsDaily.
Tomorrow read about #3-5 possible reasons for the increase of autism.