Find Information About:

Drugs & Supplements

Get information and reviews on prescription drugs, over-the-counter medications, vitamins, and supplements. Search by name or medical condition.

Pill Identifier

Pill Identifier

Having trouble identifying your pills?

Enter the shape, color, or imprint of your prescription or OTC drug. Our pill identification tool will display pictures that you can compare to your pill.

Get Started

My Medicine

Save your medicine, check interactions, sign up for FDA alerts, create family profiles and more.

Get Started

WebMD Health Experts and Community

Talk to health experts and other people like you in WebMD's Communities. It's a safe forum where you can create or participate in support groups and discussions about health topics that interest you.

  • Second Opinion

    Second Opinion

    Read expert perspectives on popular health topics.

  • Community


    Connect with people like you, and get expert guidance on living a healthy life.

Got a health question? Get answers provided by leading organizations, doctors, and experts.

Get Answers

Sign up to receive WebMD's award-winning content delivered to your inbox.

Sign Up

Autism Spectrum Disorders Health Center

Font Size

New Genetic Autism Test Beats Older Tests

Study Shows CMA Test Is More Accurate Than G-Banded Karyotype or Fragile X
WebMD Health News
Reviewed by Louise Chang, MD

March 15, 2010 -- A new genetic test for autism, known as chromosomal microarray analysis (CMA), finds more genetic abnormalities than two older tests, a study shows.

''CMA is much better than karyotyping or fragile X testing at detection -- it's at least three times better," Bai-Lin Wu, PhD, medical director of the genetics diagnostic laboratory at Children's Hospital, Boston, and a study co-researcher, tells WebMD.

While the other two tests are now standard practice, Wu and his colleagues say the new test should also be part of the initial diagnostic evaluation of patients when a clinical diagnosis of autism or autism spectrum disorder has been made or is suspected.

The study results are published online in Pediatrics.

Autism, a complex disorder, involves impairments in social interaction as well as deficits in language and communication along with rigid and repetitive behaviors. It affects about one person per 1,000, the researchers write; autism spectrum disorder (ASD) affects six per 1,000.

Comparing CMA With Other Tests

The researchers compared the results of the three tests in more than 800 patients. Among the findings:

  • The standard genetic test known as G-banded karyotype testing found abnormal results in 19 of 852 patients, or about 2%.
  • The fragile X testing found abnormalities in four of 861patients, or about 0.5%. (Fragile X syndrome is a condition associated with autism.)
  • The CMA test found abnormalities in 154 of 848 patients, or about 18%; 59 of these, or about 7%, were associated with possible or known genetic disorders.

''Karyotype testing is looking for changes visible by the microscope," Wu, a clinical molecular geneticist, tells WebMD. "CMA is looking at the molecular level."

Wu and co-researcher Yiping Shen, PhD, assistant director of the genetics diagnostic laboratory, compare karyotype testing to a map that can detect a highway that's missing in a state, and CMA testing to a map that can detect individual highway exits that are missing.

In the study, Shen and his colleagues say that CMA ''should be considered as part of the initial diagnostic evaluation of patients with ASD."

Today on WebMD

girl at window
Symptoms within the first 2 years of a child’s life.
boy playing a violin
How is this condition similar to autism?
Mother and daughter indoors playing
Play therapy may undo the disorder in at-risk babies.
preschool age girl sitting at desk
What causes this rare form of autism?
High Functioning Autism And Asperge Syndrome
Gluten Free Diet Slideshow
Mother and daughter indoors playing
man on bicycle
girl at window
Mother hugging teenage son
Understanding Rett Syndrome
Home Care Tips

WebMD Special Sections