CHD8: A Common Cause of Autism
For most of Raphael Bernier’s career as a psychologist, the children with autism that he saw in his practice were all very different from one another. They looked different, suffered from different collections of symptoms and responded to different therapies.
But within one week in 2013, Bernier saw two children with strikingly similar features. Both had large heads, sloped eyes and broad foreheads. “It looked like they could be siblings,” Bernier says. Moreover, the resemblance went beyond the physical — both suffered from serious sleep problems and gastrointestinal issues.
Bernier had encountered the two families as part of a study at the University of Washington searching for genetic clues to autism. Both children had mutations in a gene known as CHD8, which was first linked to autism in 2012. Scientists have since discovered that it’s one of the genes most commonly mutated in the condition. Nearly everyone with a harmful mutation in CHD8 has autism. (That’s not the case for other genetic variations that have been linked to the condition.)
After meeting those first two families, Bernier reached out to others in the study with CHD8 mutations. He found that they too fit the pattern. In the 27 families that he’s seen, all the individuals with CHD8 mutations have large heads, or macrocephaly; specific facial features; sleep and GI problems; and clear-cut autism. “It was exciting to see those similarities emerge,” Bernier says. Typically developing siblings and other people analyzed in genetic studies don’t have mutations in this gene, supporting the link to autism.
In a condition as diverse as autism, finding any kind of pattern is a huge boon. As a clinician, Bernier wants to be able to make predictions about how a specific child might develop or what treatments might work for her or him. But with so much variability from individual to individual, making accurate predictions has been incredibly difficult. He hopes that finding genes like CHD8 will help define genetic subtypes of autism, which could in turn aid in development of specific treatments. “We still have a lot of work to do,” Bernier says. “But we are starting to see these patterns emerge for other genes.”
The research also helps shed light on the biology of autism. For example, the CHD8 gene is active both in the brain and in the nerve cells of the gut. That might explain why a subset of people with autism also have gastrointestinal issues.
For Illana Fontes and her family, discovering that her son Trenton had a CHD8 mutation has helped Fontes connect with others families with mutations in the same gene. She belongs to a CHD8 Facebook group, where parents discuss their children’s issues and what’s worked best for them. “These families are the experts in their kids, so it’s best to have them connect with the other experts,” Bernier says. “I am excited to be able to connect families in that way.”