A blood test may be able to accurately identify children with autism as young as 12 months, new research suggests.

In a study of more than 200 toddlers, researchers were able to distinguish between those with and without the developmental disorder in at least three-quarters of cases by testing blood samples.

Currently, autism is diagnosed through clinical observation and most kids on the spectrum are not identified until after age 4, according to the U.S. Centers for Disease Control and Prevention.

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Finding a biomarker or other method to pinpoint autism at earlier ages is critical, researchers say, in order to help children get treatment while they’re young when it can be most effective.

For the study, researchers took blood samples from boys ages 1 to 4, some of whom had autism and some did not. They assessed RNA expression levels in leukocytes, or white blood cells, to differentiate children with autism from typically-developing kids and those with other types of developmental delays.

The test was conducted with two separate sets of boys. The first group included 147 children and was accurate in 83 percent of cases, while the second group had 73 participants and had a 75 percent accuracy rate, according to findings published online this month in the journal JAMA Psychiatry.

The children in the study were representative of the range of kids seen at a typical community clinic, researchers said, suggesting that a blood test of this nature could one day be effective at flagging children with autism in such an environment.

“A major challenge is the difficulty of accurately diagnosing ASD, which is very heterogeneous, at an early enough age to implement the most effective treatment,” said Eric Courchesne, an author of the study and a professor of neurosciences and director of the Autism Center of Excellence at University of California, San Diego School of Medicine.

“Our study showed that a blood-based clinical test for at-risk male infants and toddlers could be refined and routinely implemented in pediatric diagnostic settings,” Courchesne said.