Genetics May Help Explain Autism

Children with a rare chromosome abnormality may be 100 times more likely to develop autism, says a study published in the New England Journal of Medicine today. A team of researchers says it has found a genetic anomaly on one chromosome that makes up the DNA of human beings.

For years, it's been a mystery. The number of children with autism was growing, but researchers could not understand why.

Some parents and advocates suspected the cause was chemical. They wondered if there might be a link between autism and mercury, which was used for years as a preservative in childhood vaccines.

But a study published this past Monday says no. Autism rates in the state of California continued to increase for children between the ages of 3 to 12, even after mercury was removed from most childhood shots in 2001. The study was published in the journal Archives of General Psychiatry.

Dr. David Miller of Children's Hospital in Boston said, "We think that this chromosome 16 region may have some genes that are very important in brain development, and when changes happen in those genes, it may be the cause of many cases of autism."

Autism today appears in one child out of 150.

"In the long run, finding these genetic regions, and the genes within them, may eventually lead us to genetic pathways that could be a target for some type of therapy," Miller said.

But Miller also said this does not rule out the possibility that autism may have other causes — some environmental.

"We have to figure out what is it about the combination of this chromosome 16 with other genetic factors, or other environmental factors," he said.

The doctors who did the work acknowledge that autism may still have many unknown causes, but they say they may have found an important clue.