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Categorizing Autism Based on Genes

Emily Singer

One of the challenges in diagnosing and treating autism lies in its diversity — people with the condition have a broad spectrum of symptoms of varying severity. Raphael Bernier and collaborators at the University of Washington in Seattle are searching for the commonalities.

The researchers are taking a gene-focused approach, looking for shared symptoms in people with autism who have changes in the same gene. The project, called the TIGER (The Investigation of Genetic Exome Research) study, has a broad scope. It includes children with changes in any of roughly 35 autism-linked genes.

Bernier’s team hopes this type of analysis will help differentiate subtypes of autism. A more comprehensive picture of the symptoms linked to a specific gene can help families and physicians know what to expect. In the long term, the findings may guide development of individualized therapies.

TIGER researchers track a comprehensive suite of symptoms: individuals’ motor and cognitive function, medical history, sleep and gastrointestinal problems, as well as morphology, such as unusual facial features. For example, scientists rigged a room with multiple cameras to capture 3-D images of the head and face. The system can measure subtle features, such as curvature of the ears or distance between the eyes, revealing whether changes in a specific gene lead to certain facial features. Bernier refers to this technology-laden space as the “rocket-ship room.” “We can do all these measurements you can’t do for a kid who is normally squirming and doesn't like to be touched, he says.

EEG tests, for example, capture data on participants’ brain activity. And psychological testing measures language abilities, learning, memory and other factors. The researchers run the same tests on all the children, making it easy to compare outcomes among genes.

Over the last four years, Bernier’s team has assessed about 100 children. “There definitely appear to be some interesting common features,” Bernier says. “I already see a clear value in this approach.”

Children with changes in the CHD8 gene, for example, tend to have large heads and sleep and gastrointestinal problems. (For more on this gene, see CHD8: A Common Cause of Autism.)

For many autism-linked genes, too little data exists to develop clear guidelines for physicians. They don’t yet know how best to use genetic testing results to guide treatment. Bernier hopes results from the TIGER study will change this.

“When we can find commonalities within a gene group, we can start thinking about clinically relevant symptoms to address,” Bernier says. For example, physicians now know to monitor children with changes in the CHD8 gene for gastrointestinal issues.

For most genes, the TIGER team has studied only a handful of cases. They need more participants to create a reliable picture of the outcomes for each gene. “It’s hard to say we’ve seen enough families to be confident about a particular profile,” he says.

One of SPARK’s goals is to connect scientists and people who want to participate in research. TIGER is now collaborating with SPARK, and Bernier hopes this relationship will bring more people into the study. “Our goal is to work with another 100 people over the next four years,” he says.

Families who enroll in the study typically make a sponsored trip to Seattle for testing. “It’s critical for us that families have a good time; we talk a lot about that as lab,” Bernier says. “They spent a lot of time and energy to get on a plane. I appreciate every family’s willingness to do that.”