ST. LOUIS, Aug. 22 (UPI) -- Researchers are linking rare changes in common brain chemicals and networks of genes with some of the symptoms of autism.
Many genes have been implicated in causing autism. But "to date there has not been a single gene with a major effect," said Dr. Eric Hollander, director of the autism center at Mount Sinai School of Medicine in New York.
Dr. Judith Miles, head of medical genetics at the University of Missouri at Columbia, says some children get autism because their genes guide their brains to develop in a nontypical way. Miles calls the genetically based disorder "essential autism."
But environmental insults, such as toxins, and developmental missteps caused by hormone surges or other factors may also push a child into autism, Miles says. She calls this type of disorder "complex autism."
Autism actually may be multiple different genetic syndromes, researchers said.
Autism is not a "you have it or you don't" disorder, said Dr. Richard Todd of Washington University said. Instead, it is a highly inheritable continuum of traits, much like height or high blood pressure.
