A defective gene responsible for abnormal social behavior, a characteristic of autism, has been discovered. The research advances the knowledge about changes in the brain found in people with autism. The study could be used to find treatments for autism.

The research found that just one abnormal gene disturbs energy flow in the brain cells and severely affects key areas of the brain.

"A number of genes and environmental factors have been shown to be involved in autism, but this study points to a mechanism -- how one gene defect may trigger this type of neurological behavior," said Cecilia Giulivi, professor of molecular biosciences in the UC Davis School of Veterinary Medicine and lead author of the study.

Researchers used mice models to study the effects of this gene called pten. They genetically modified mice so that they had a defective copy of this gene and as a result a deficiency of the protein that the gene codes for. They found that the effects of this tweaking occurred within 4 to 6 weeks after birth.

When the mice were 20 to 29 weeks old, they avoided social connections. Researchers found that DNA damage had occurred and the functions of mitochondria (the energy factory of the cell) were disrupted. Mice whose gene wasn't altered displayed no anti-social or abnormal behavior and didn't have damaged mitochondria.

Researchers also found that interaction between defective pten gene's protein and protein encoded by another gene called p53 caused a hike in the stress levels in the mitochondria. This in turn led to abnormal level of energy production in the areas of brain like cerebellum and hippocampus that are involved with social behavior and learning.

Defective pten's insufficient protein production triggers a chain reaction that damages other proteins as well causing severe loss of learning abilities.

"Once you understand the mechanism, that opens the way for developing drugs to treat the condition," Giulivi said.

The study is published in the journal PLOS ONE.