A relatively new genetic test is much more likely to detect autism than two more popular methods, though no gene test flags the vast majority of people with autism spectrum disorders, researchers said Monday.

In genetic testing of 933 people with some form of autism spectrum disorder, researchers found that 7.3 percent were identified using the newer test called chromosomal microarray analysis, or CMA.

Though this remains a small portion, the test pegged significantly more people than two older tests that are more commonly used. Among the same group of subjects, a method called karyotyping identified 2.23 percent, while fragile X testing found just 0.46 percent, researchers reported online Monday in the journal Pediatrics.

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The study, which is the largest ever conducted looking at genetic testing on those with autism, will be published in the journal’s April issue.

Currently CMA is considered a second-tier test because it is new and often is not covered by insurance.

“Based on our findings, CMA should be considered as part of the initial clinical diagnostic evaluation of patients with ASDs,” says Bai-Lin Wu, of Children’s Hospital Boston who is one of the study authors.

Scientists can identify a known genetic cause for just 15 percent of those with autism today, so even the most successful gene test will not pick up on the majority of those with the disorder.

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