People with mutations in certain genes have strong chances of developing autism, a new research on Autism Spectrum Disorder shows.
A collaborative study conducted by 13 institutions around the world found that mutation in the CHD8 gene is associated with autism marked by gastrointestinal disorders, a larger head and wide set eyes.
Past researches have emphasized that genetic events like Fragile X, which accounts for a number of autism cases, are associated with other deficiencies, such as intellectual disability, more than autism.
"We finally got a clear cut case of an autism specific gene," said Raphael Bernier, the lead author, and University of Washington associate professor in the Department of Psychiatry and Behavioral Sciences and the clinical director of the Autism Center at Seattle Children's.
For the study, researchers examined 6,176 children with ASD and they found 15 had a CHD8 mutation. The team noted that all these cases had similar characteristics in appearance and issues with sleep disturbance and gastrointestinal problems. Researchers then also interviewed all 15 cases with CHD8 mutations.
Following this, the team then collaborated with Duke University researchers involved in zebra fish modeling. They disrupted the CHD8 gene in the fish and noticed that the fish developed large heads and wide-set eyes. The fish were given fluorescent pellets to eat. Researchers found that the fish had problems removing food waste and were constipated.
According to Bernier, this is the first time researchers have shown a decisive cause of autism to be due to a genetic mutation. He also stated that although less than half a percent of all kids have this kind of autism related to the CHD8 mutation, there are lots of implications from this study. "This will be a game changer in the way scientists are researching autism," he said.
The team said the study findings could pave way for a "genetics-first approach" that could discover hundreds more mutations and lead to genetic testing. Genetic testing could be offered to families as a way of guiding them on what to expect and how to care for their child. Currently, autism is diagnosed based on behavior, said Bernier.
Bernier advised the clinicians to concentrate on the small population with this CHD8 mutation and provide targeted treatment.
Autism has been associated with various genetic events with the most common being chromosomal re-arrangements, called "copy number variations," in which a chunk of chromosome is copied or deleted. But no one rearrangement affects more than 1 percent of all autism cases. While these copy number events are associated with autism, they do not have a definitive link, or as they say among researchers, a "strong penetrance."
The CHD8 gene mutation is the first gene mutation to show a very strong penetrance linked to a certain subtype of autism.
The study results were published in Cell magazine: 'Disruptive CHD8 Mutations Define a Subtype of Autism in Early Development.'