Researchers studying two seemingly unrelated conditions — autism and cancer — have unexpectedly converged on a surprising discovery. Some people with autism have mutated cancer or tumor genes that apparently caused their brain disorder.
Ten percent of children with mutations in a gene called PTEN, which cause cancers of the breast, colon, thyroid and other organs, have autism. So do about half of children with gene mutations that can lead to some kinds of brain and kidney cancer and large tumors in several organs, including the brain. That is many times the rate of autism in the general population.
“It’s eerie,” Evan Eichler, a professor of genome science at the University of Washington, said about the convergence.
He and others caution that the findings apply to only a small proportion of people with autism; in most cases, the cause remains a mystery. And as with nearly all genetic disorders, not everyone with the mutations develops autism or cancer, or other disorders associated with the genes, like epilepsy, enlarged brains and benign brain tumors.
But researchers say the findings are intriguing, given that there are no animals that naturally get autism, no way of analyzing what might cause autism in developing brains and no cure. The newly discovered link has enabled scientists to genetically engineer mice with many symptoms of the human disorder.
And it has led to the first clinical trial of a treatment for children with autism, using the drug that treats tumors that share the same genetic basis.
Richard Ewing of Nashville, Tenn., a 10-year-old who has a form of autism caused by a tumor-causing gene, is among those in the new study. His parents, Alexandra and Rick Ewing, know he is at risk for tumors in the brain, heart, kidney, skin and eyes. But that bad news was tempered by his eligibility for the clinical trial, which has only just started.
“There is a big difference between us and the rest of the autism community,” Rick Ewing said. “We have an honest-to-God genetic diagnosis.”
Not everyone agrees that the discovery is so promising. Steven McCarroll, a geneticist at Harvard, notes that autistic children with the cancer gene mutation have “a brain that is failing in many ways.” Autism in these children could be a manifestation of a general brain malfunction, he said, adding, “The fact that autism is one of the many neurological problems that arise in these patients doesn’t necessarily tell us anything penetrating about the social and language deficits that are specific to autism.”
But other scientists who are not involved in the research that produced these findings say the work is changing their understanding of autism and why it develops. Like cancer, autism can involve unregulated growth of cells, in this case neurons in the brain. NYT