Diagnosing autism is a complex and often inexact science that can involve multiple rounds of behavioral testing.
But a new study has found that two genetic tests may help doctors and parents identify certain genetic mutations that are linked to the disorder, providing a clear molecular diagnosis.
Researchers believe that the information could potentially help parents who have one child with autism spectrum disorder identify whether any future children are at increased risk, and also lead to the development of more personalized treatment plans.
In the new study, published in the Journal of the American Medical Association (JAMA) on Tuesday, a team of investigators with the Hospital for Sick Children in Toronto, Canada, performed two relatively new genetic tests on a group of 258 children who had already been diagnosed with autism to better gauge how capable the tests are at spotting genetic mutations that may contribute to autism.
Of the 258 children, more than 9 percent received a molecular diagnosis from a test known as "chromosomal microarray analysis," or CMA. A major 2010 study showed CMA to be more effective than previously available genetic tests for autism. Roughly 8 percent received a diagnosis from a newer test, called "whole-exome sequencing," or WES. (The two tests provide different, but potentially complementary molecular information.)
Combined, the tests provided roughly 16 percent of families with some genetic clues as to why their children's autism developed.
That number might sound low, but Stephen Scherer, director of the Center for Applied Genomics at the Hospital for Sick Children and an author on the study, told The Huffington Post that there is a significant range in the level of impairment associated with autism, and likely many factors that contribute to its development, both genetic and otherwise. The researchers also found that among a subgroup of children with certain physical anomalies that are often linked to autism, the rate of molecular diagnoses was higher -- at 37 percent.
"The first thing parents want to know is why autism came about in their kid, and 10 years ago, we couldn't tell them anything," Scherer said. "Now, for at least 15 percent [of parents], we can tell them something. That's really important."
Scherer said parents' second question is often about whether any other children they have are at greater risk for autism. Because siblings share many genetic similarities, the new tests could provide parents with one child who received a molecular diagnosis a better understanding of that risk.
In an editorial accompanying the new study, Judith Miles, a researcher with the Thompson Center for Autism and Neurodevelopmental Disorders in the Department of Child Health, University of Missouri Health Care, wrote that the new findings show that doctors who treat children with autism should help arrange for testing that may help provide additional information about whether genetic factors are at play.
"It is incontrovertible that precise diagnoses pave the way to better medical care, improved surveillance, better functional outcomes and informed genetic counseling," she wrote.
"Children with ASD are often grouped together and the opportunity to provide patient-specific care is missed," Miles added.
Indeed, because much of the variability in the types of symptoms accompanying autism is believed to stem from differences in genetic mutations, Scherer said the hope is that clinicians will be able to use genetic testing to help classify autism into more specific subgroups, so children can receive more targeted treatment. He added that the two tests are increasingly available in major medical centers, and that parents should feel empowered to ask for them after their child has undergone behavioral testing, but said that insurance coverage can be limited.
"Awareness is the key," Scherer said. "Parents and doctors should know about these tests, because in 15 to 16 percent of families, they can add information that's really quite relevant."
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