Could a blood test detect autism? Study aims to answer

A simple blood test might be able to reveal whether a child has autism, according to researchers who recently launched a study to evaluate such a test.

The study, which began this week and involves 660 participants at 20 facilities around the United States, will examine whether the test can accurately distinguish between children who have autism and children who have other developmental delays, the researchers said.

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While the blood test by itself cannot diagnose an autism spectrum disorder (ASD), the researchers hope it will speed up the time it takes to diagnose the condition, which can be a lengthy process.

"If a blood test could indicate ASD risk, it would help families and physicians know when to refer children to an ASD expert, potentially leading to earlier treatment and better outcomes," Dr. Jeremy Veenstra VanderWeele, an assistant professor of psychiatry at Vanderbilt University, said in a statement.

The study is being funded by SynapDx, the company that hopes to develop and market the test.

Autism spectrum disorders are a range of developmental disorders characterized by social impairment, language difficulties and repetitive behaviors. Currently, ASD is diagnosed by evaluating a person's behavior and taking into account their medical history.

The new test could provide an objective marker for autism that would be used in conjunction with clinical evaluation, the researchers said. The test looks at gene expression — whether a gene is "turned on" or not — and is aimed at distinguishing between children who have autism and those who don't.

In a 2012 study of a similar test involving 170 children with autism and 115 children without autism, the test could accurately identify autism in two-thirds of children who had the condition. That test, which looked for differences in the expression of 55 genes, was later licensed to SynapDx.

The earlier study indicates that the blood test for autism is not accurate enough to reliably distinguish between the children who had autism and those who did not, said Dr. Andrew Adesman, chief of developmental and behavioral pediatrics at Steven & Alexandra Cohen Children's Medical Center of New York.

Additionally, researchers still need to prove that the test works in children younger than school age, which would be important if the researchers hope to use the test as an early indicator of autism, Adesman said. The average age of a child diagnosed with autism is 4.5 years, while the average age of the children in the study was 8. With time, the test will likely be refined so that it's more accurate, but won't replace a clinical diagnosis, Adesman said.

Even if the test proves accurate in identifying which children have autism, the jury is still out on whether it would really be helpful for doctors and patients, experts say.

"Autism is a very heterogeneous disorder," meaning its symptoms and severity can vary widely depending on the individual child, said Dr. Roberto Tuchman, director of the Autism and Neurodevelopment Program at Miami Children's Hospital. So a test that tells you a child has autism "doesn't mean much" in terms of how the child will develop or respond to therapies, Tuchman said.

"I don’t know that it's going to be a game changer from day-to-day practice," Tuchman said of the test.

If doctors don't find the test useful, it's possible that it could have the same fate as another blood test developed for schizophrenia in 2010. That test was 83 percent accurate in diagnosing schizophrenia, but because physicians couldn't find a use for it — doctors said they could accurately diagnose schizophrenia without the help of a blood test — it was taken off the market, according to a Wall Street Journal report.

Tuchman noted that a doctor who was concerned enough about a child's development to order a blood test for autism should start early treatments anyway, because such treatments would help any child who was not developing properly, regardless of whether he or she has autism.

However, Tuchman supported the idea of an autism blood test, saying the more we know about autism genetics, the better we will be able to understand and treat the disorder.

Adesman said a blood test that indicated a child was genetically at risk for autism could help family members plan for the future, and spur doctors to evaluate the child for the condition on a more frequent basis.

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