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New Genetic Autism Test Beats Older Tests

Study Shows CMA Test Is More Accurate Than G-Banded Karyotype or Fragile X

CMA an 'Excellent' Test

The new study confirms smaller studies finding that CMA is an excellent test, says Randi Hagerman, MD, medical director of the MIND Institute at University of California, Davis, and an autism expert.

''This [new study] demonstrated that the CMA picked up abnormalities at a much higher rate [than other tests]," says Hagerman, who reviewed the findings for WebMD.

The patients studied, she says, were a relatively high functioning group of people with ASD. That population, she says, ''reflects more closely what clinicians are seeing now in their office." She says the rate of intellectual disabilities of those with autism and ASD has gone down in recent years.

The bottom line of the study? "You should do genetic testing on everyone with autism or ASD," Hagerman says. "That's been the recommendation for years." With the new study findings, she says, the message is clear that "you should include CMA."

Doing all three tests would be ideal, she says. But if you can only do two, she would pick fragile X and CMA. If someone has autism or ASD, she says, the CMA test "is the No. 1 test to yield an abnormal result."

Limits of Autism Testing

Genetic testing can help parents get early intervention, Wu says. And it can help them in family planning, predicting the risk of having another affected child.

But genetics still only explains a minority of autism and ASD cases, Wu says, perhaps up to 15%. CMA can help detect about half of that 15%.

One other obstacle, Hagerman and others say, is that insurance does not always cover the costs. Fees vary, but the CMA alone can cost about $1,200 in California, Hagerman says.

Andy Shih, PhD, a spokesman for Autism Speaks, cautioned in an email to WebMD that "this CMA methodology is not yet ready for commercial application and does not specifically test for autism and therefore is a tool of limited value for concerned parents and families."

He calls for more research on the new test, "especially on how to interpret the findings from CMA relative to autism risk, before it can help families make more informed health care decisions."

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