Research by a team at Duke University reports that a combination of malfunctioning genes increases the likelihood of autism in African Americans. The study, whose senior author is Margaret Pericak-Vance, PhD, director of the Duke Center for Human Genetics, is published in the online version of Neurogenetics. An article in today’s SheKnows.com summarizes the study:
In their study, the Duke researchers analyzed the genes of 54 African American families and 557 Caucasian families in which a member had autism. They searched along chromosome 15, which had previously been linked to autism, for genes that regulate a brain chemical, or neurotransmitter, called GABA.
GABA inhibits nerve cells from firing once their message has been transmitted. In this way, the neurotransmitter acts as an information filter that prevents the brain from becoming over-stimulated.
If the GABA system malfunctions, the brain can be flooded with sensory information that overwhelms the brain’s processing capabilities, leading to some of the behaviors that characterize autism, said Michael Cuccaro, Ph.D ., a Duke clinical psychologist and study co-author.
The researchers found that in African Americans and Caucasians, the interaction of two malfunctioning GABA receptor genes — GABRB1 and GABRA4 — can increase the risk of autism. GABA receptors are docking sites on the surface of brain cell neurons. GABA binds to these docking sites and inhibits the neurons from firing.
“We found that GABRA4 increases of the risk of autism, and its interaction with GABRB1 further increases the risk of autism,” Pericak-Vance said.
Scientists think that some 100 genes may be involved in autism. Dr. Pericak-Vance further notes that different ethnic groups possess “unique genes that can interact with autism-associated genes to slightly alter the course of the disease”—-it seems that the complicated story of autism genetics is even more complicated.