Parents often report that tummy troubles and autism go hand in hand. Some have even suggested that special diets can reduce autism symptoms. But many experts have dismissed the connection as mere coincidence or have attributed the overlapping conditions to different genetic or environmental factors.
Now new research, published in the March Pediatrics, shows that there is a genetic link between autism and gastrointestinal disorders. It’s unclear whether this genetic link means that an environmental therapy such as diet could boost brain function or if just feeling better could be responsible for improved behavior.
Researchers from Vanderbilt University had previously linked a genetic variant in the control panel of the MET gene to autism. In the general population, some people have the DNA letter G in a particular position in the control panel, which determines whether the MET gene is active. Other people have a C in that position. That variant of the gene, known as the MET C allele, turns down production of MET, a protein involved in brain development, gut repair and other body functions. Children who inherit copies of MET C from both parents have more than twice the risk of developing autism as children who get the G variety from both parents.
In the new study, the Vanderbilt team and additional colleagues found that children with autism who have two copies of MET C are also more likely to have gastrointestinal problems than people who have two copies of the G variant or a combination of G and C. The study is the first to demonstrate a possible genetic cause for the co-occurrence of autism and digestive tract problems.