By Jon Singer

Researchers at Stony Brook University Medical Center have uncovered a new gene that could answer a few questions about autism.

A team of pathologists that included six Stony Brook faculty members reported the existence of the gene, called contactin 4, in a study published in March. “Contactin 4 plays an essential role in the formation, maintenance and plasticity of neuronal networks,” says the study, which was published in The Journal of Medical Genetics.

After studying ninety-two participants from eighty-one different families, the researchers found three children with abnormal contactin 4 in their genomes.

Despite the small fraction — of three in ninety-two — doctors involved in the extensive undertaking of genetic research call this progress. Dr. Andy Shih, Vice President of Scientific Affairs at Autism Speaks, a New York City-based advocacy organization, said multiple genes are associated with autism. Both Shih and Dr. Eli Hatchwell, corresponding author of the study, said that more than 100 genes could be related to autism.

“The challenge will be to test for all of these in affected individuals, in order to better classify the type of autism they have and to be better able to treat them, whether via education or specific drug therapy,” Hatchwell said in an email interview.

The challenge comes at a time when advocacy organizations say that autism rates are increasing, although government organizations have said there is not enough information to make any conclusions. The different perceptions have led to debate as the rates swell. Some parents of autistic children have argued that mercury contamination, especially from childhood vaccines, casues autism. But the American Medical Association says there is no link among mercury, vaccines and autism.

The Stony Brook study refers to autism as “Autism Spectrum Disorder,” and researchers put an emphasis on “spectrum.” Shih pointed out that the definition of autism has broadened in the past ten years to include disorders such as Asperger’s Syndrome, which has been described as a milder form of autism. This broader definition has been the result of refined diagnostic techniques, some of which involve genetic testing and others that are simple observations of a child’s behavior.

“Our approach is to try and find as many genetic causes as possible,” Hatchwell said. “The unexplained cases that remain after are potentially the result of environmental insults.”

Hatchwell said the study could not have been done ten years ago, as the technology of microarray (a small glass slide onto which tens of thousands of DNA sequences are printed) did not exist. “The research is significant because understanding the biological basis of a disease is a sine qua non for future therapeutic intervention,” Hatchwell said.

Shih said that this genetic study is worth following up and should be replicated before it is accepted. “These genes, when they are discovered, then to be risk factors, not causes,” he said.

More importantly, Shih continued, people need to know what percentage of the autism community carries the probability of a contactin 4 disorder. Because only ninety-two children were tested, the Stony Brook study is too small.

Hatchwell said there’s a belief that eventually the number of genes that are known to cause autism will break the 100 mark. “Our study adds to the growing list of genes that cause at least some cases of autism,” he said.