Autism is not just a disorder of the brain, study suggests
Autism spectrum disorders (ASDs) are characterized by impaired social interactions and repetitive behaviors, often accompanied by abnormal reactions to sensory stimuli. ASD is generally thought to be caused by deficits in brain development, but a study in mice, published June 9 in Cell, now suggests that at least some aspects of the disorder--including how touch is perceived, anxiety, and social abnormalities--are linked to defects in another area of the nervous system, the peripheral nerves found throughout the limbs, digits, and other parts of the body that communicate sensory information to the brain.
"An underlying assumption has been that ASD is solely a disease of the brain, but we've found that may not always be the case," says senior author David Ginty, a Professor of Neurobiology at Harvard Medical School and a Howard Hughes Medical Institute Investigator.
"Advances in mouse genetics have made it possible for us to study genes linked to ASD by altering them only in certain types of nerve cells and studying the effects."
In the new study, the researchers examined the effects of gene mutations known to be associated with ASD in humans. In particular, they focused on Mecp2, which causes Rett syndrome, a disorder that is often associated with ASD, and Gabrb3, which also is implicated in ASD. They looked at two other genes connected to ASD-like behaviors as well.
These genes are believed to be essential for the normal function of nerve cells, and previous studies have linked these mutations to problems with synaptic function--how neurons communicate with each other.