The researchers at Duke University Medical Center found higher-than-usual numbers of gene-regulating molecules called methyl groups in a region of the genome that regulates oxytocin receptor expression in people with autism.
"In both blood samples and brain tissue, the methylation status of specific nucleotides in the oxytocin receptor gene is significantly higher in someone with autism, about 70 percent, compared to the control population, where it is about 40 percent," said co-lead author Simon G. Gregory, Ph.D., assistant professor in the Duke Department of Medicine.
Oxytocin is a hormone secreted into the bloodstream from the brain, and also released within the brain, where it has a bearing on social interaction. Previous studies have shown that giving oxytocin can improve an autistic person's social engagement behavior and it is being explored as a potential treatment of the disorder. Higher methylation of the oxytocin receptor gene may make a person less sensitive to the hormone.
The findings by Dr. Gregory and his colleagues will potentially provide information about which individuals will respond better to treatment with oxytocin.
"We are excited about our findings because they represent one of the few occasions in which a mechanism other than genetic susceptibility or genome instability is implicated in the development of autism, Gregory said.
"These results provide a possible explanation of why social isolation forms part of the autism spectrum – because an autistic individual's ability to respond to oxytocin may be limited," Gregory said.
MEDICA.de; Source: Duke University Medical Center