For years autism has baffled researchers and devastated families. Autism typically appears in the first three years of life. Symptoms include problems with communication, difficulty forming relationships and the development of strong obsessions. The disability can be extremely mild or so severe it causes profound mental retardation or lack of ability to socialize. Now three separate studies, researching completely different theories, all ended up focusing on genetic factors involved with autism. VOA's Carol Pearson has more.

The autism studies focused on the genes related to speech since delays in learning to speak are symptoms of the disorder.

Doctors in Massachusetts found rare genetic abnormalities on chromosome 16 that are 100 times more common among people with autism. Dr. David Miller says, "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."

However, most people with autism do not have this mutation, which means many other genes may be involved. Doctors from Johns Hopkins University found a different gene -- one called CNTNAP2 -- chromosome seven -- which increases the risk of autism when this gene is mutated.

Researchers say this gene mutation is inherited from mothers. Doctors have long suspected a genetic link with autism. Dr. Marie Savard explains. "It's a very strong genetic link. If you have, for example, identical twins, one has autism. There's up to a 90 percent chance that the second twin will have it."

Researchers at both Johns Hopkins University and the University of Illinois studied families with two or more autistic children. The Gaston family includes autistic triplets.

They found a single change in chromosome seven made children more vulnerable to developing autism. "Finding these genetic regions could be a target for some type of therapy," Dr. Miller said.

The researchers do not know the cause of autism, but they say that once they uncover the genetic links to the disorder they may be able to treat it.

The U.S. Centers for Disease Control and Prevention says one out of every 150 babies born in the United States are affected by autism.