A study involving more than 100 families prone to autism revealed six new genes that seem to underlie the disease, which means researchers might find new alternative to treat it.

Autism is usually characterized through social isolation, speech problems and repetitive activities.

The researchers, who published their study in the journal Science, confirmed once again that autism is not a single disease, but a condition that can be caused by several genetic and environmental factors. They added more evidence to the fact that autism involves the process by which some networks of brain cells expand, while many others die in the first few years after birth.

As three of the six genes identified in the new study are regulated by “neuronal activity,” it seems that changing the experiences of autistic children might help them improve their condition.

“The genes implicated in our study are ones that interact with the environment and are involved in how the brain converts what it sees from the environment,” said Christopher A. Walsh, a neurologist and chief of genetics at Children's Hospital in Boston who headed the team. "If we can activate those genes by other mechanisms, we might be able to help the kids.”

Other researchers also agreed that these “experience genes” can be helpful enough to rise the hopes for finding a treatment for the disorder affecting one in every 150 children in the United States (according to the U.S. Centers for Disease Control and Prevention’s estimates).

Dr. Christopher Walsh and Dr. Eric Morrow of Harvard Medical School in Boston and colleagues studied 104 families in the United States, Pakistan, Turkey, Jordan, Saudi Arabia and Kuwait. All families included members who suffered from autism and also, in 88 of the families, first-cousin marriages were common.

Such types of marriages can cause recessive disorders occur more often.

“Marriage between first cousins increases the prevalence of neurological birth defects by about 100 percent,” the researchers wrote in their report.

Walsh said that autism symptoms emerged at an age when the brain is refining the connections between neurons, based on a child’s experience. So, depending on “experience-triggered neural activity,” certain important genes are turned on or not. When there are genes that are not turned on during this process, “autism-associated mutations” are very likely to occur.

An important finding is that the mutations did not have as result missing or damaged genes, but only ones that are turned off, therefore inactive.

This means, as Morrow explained, that the genes do not need to be replaced, but only reactivated, probably by use of medication.

Walsh, who also is a Howard Hughes Medical Institute investigator, said that the study has shown that complex learning environments can be of help for children suffering from autism. Such developed training might activate certain pathways in the brain that could turn on the necessary genes.

Autism is a disorder related to Asperger’s syndrome, which can cause mental retardation in up to 70 percent and seizures in 20 to 25 percent of cases.

"At the moment, we understand the genetic causes of 15 to 20 percent of autism," Walsh said. "The remaining 80 percent remain unexplained."