New Genetic Test for Autism Spectrum Disorders More Effective

Published: Tue 16 Mar 2010

Lucas Eichmann

A genetic autism test currently considered a secondary approach might be able to identify the root causes of the condition three times faster than the genetic screening regarded as a first-tier test, reports a new study.

The scientists began the study to see how the newer screening, known as chromosomal microarray analysis (CMA), compares with the tests currently regarded by the American Academy of Pediatrics as first-tier approaches to G-banded karyotype and Fragile X screening. The researchers hope that the new study will launch the test to first-line status in pinpointing the genetic causes of autism spectrum disorders.

The Children's Hospital Boston developed the CMA test in 2006, and the CMA has been assessed over the last couple of years.

Becoming a First-Tier Test

"We think it should absolutely be a first-tier test for autism," explained Dr. David Miller of Boston's Children's Hospital and co-author of the study. "It is already being used, but it is not being used in every patient all over the country uniformly."

Another study co-author, Bai-Lin Wu of Harvard Medical School, reported that the CMA test allows physicians to discover underlying genetic causes in about seven percent of autism cases.

"From the number itself, 7 percent does not look like a large percentage," Wu explained. "However, there are a lot of kids being diagnosed with autism, so it is 7 percent of a very large number."

More specifically, there are roughly four million births in the U.S. each year. The rate of autism is about one percent according to the Centers for Disease Control and Prevention. That means that about 40,000 babies per year will be born with autism spectrum disorders.

Success of Current Tests

Wu explained that the current genetic tests in use may only identify two percent of the genetic aberrations that might contribute to the development of autism. In other words, scientists can identify genetic causes of autism in only about 800 cases per year, but adding the secondary CMA test would contribute an additional 2,000 explanations.

"Compared to [these tests], this one worked more than three times as effectively," Wu explained. "This may mean we detect much more genetic changes that we have not been able to find yet."

The test might also bring an end to the guilt parents feel about their child's autism, says Dr. Leonard Rappaport, another of the study's co-authors.

"As in most things in life, people search for the reason why something happened," said Rappaport. "Mothers are still blamed for their children's developmental problems by extended families, and families blame themselves for secret things they do not even reveal to us. As we find diagnoses that cause ASD, people will worry less about things, such as immunizations, despite there being no data to support them."