One of the most agonizing questions that parents of children with autism ask iswhy? Now, a growing number of genetic tests are providing some answers.

Scientists say that roughly 20 percent of autism cases can be linked to known genetic abnormalities, and many more may be discovered.

Pinpointing a genetic explanation can help predict whether siblings are likely to have the disorderand even point to new, targeted treatments. Last week, for example, researchers reported that an experimental drug, arbaclofen, reduced social withdrawal and challenging behaviors in children and adults with Fragile X syndrome, the single most common genetic cause of autism.

Related: Experimental drug to treat Fragile X syndrome shows promise

No single blood test or brain scan can diagnose autism spectrum disordersin part because environmental factors also play a major role. But once a child is diagnosed, on the basis of symptoms and behavioral tests, researchers can work backward looking for genetic causes.

Both the American Academy of Pediatrics and the American College of Medical Genetics recommend that all children diagnosed with ASD be tested for Fragile X Syndrome and other chromosome abnormalities. The newest tests, called chromosomal microanalysis, can identify submicroscopic deletions or duplications in DNA sequences known to be associated with autism. Together, these tests find genetic explanations for more than 10 percent of autism cases.

Experts estimate that 400 to 1,000 individual genes may play a role in the complex neurological issues involved in autism. Tests are proliferating that look for mutations in some of those genes, thanks to new technologies that let scientists sequence many genes at once.

Mount Sinai School of Medicine in New York City, for example, is offering a new blood test that examines 30 different genes for mutations known to be associated with autism or other developmental delays.

Some autism-related genetic disorders also carry a high risk of cancer, seizures, heart disease or other health problems, so knowing about them allows families and physicians to be vigilant for such issues.

Identifying genetic causes can also help families find support groups, research programs and potential treatments tailored to their child's specific needs. For example, one of the abnormalities Mount Sinai tests for is the SHANK3 mutation on chromosome 22. It causes an autism-spectrum disorder and Phelan-McDermid Syndrome, in which communication between nerve cells is disrupted, impairing learning and memory. Researchers at Mount Sinai found that an insulin-like growth factor could reverse that disruption in mice and are now testing it in children aged 5 to 17 with SHANK3 mutations.

Read more:
New tests indicate progress in identifying the genetic roots of autism

Comments are closed.