In recent years, the number of children diagnosed with autism in the United States has skyrocketed, the researchers noted. One of the most heritable of complex genetic disorders in neuropsychiatry, autism is characterized by impairments in social interaction and communication and restricted and repetitive patterns of interest or behavior.
While many previous studies have identified possible genes with links to autism, there remains no single gene with a consistent connection to the disease, Pericak-Vance said.
Multiple lines of evidence, including alterations in levels of GABA and GABA receptors in patients with autism, have implicated the brain mechanism in the disease. Furthermore, there is evidence that GABA plays a key role in the early development of the brain.
Earlier research by the Duke team and other researchers linked a portion of chromosome 15 to autism risk. That region harbors genes that code for three GABA receptors.
Since one of the primary functions of GABA is to inhibit nerve cells from firing, it plays a key role in telling the body to "slow down.". The GABA system therefore acts as a sort of information filter, preventing the brain from becoming over-stimulated, the researchers explained.
"Impairing the GABA system could overwhelm the brain with sensory information, leading to both the behavior and the pattern of cell damage that emerges in autism," said John Hussman, Ph.D., a study co-author and president of The Hussman Foundation, one of the groups that funded the study.
The researchers examined 14 genes that encode portions of the GABA receptor in 470 Caucasian families. Of those families, 266 included more than one person wi
Source:Duke University Medical Center