WebMD Health News, By Daniel J. DeNoon and reviewed by Laura J. Martin, MDA particular "misspelling" in the genetic code of individuals with ADHD may make brain cells more excitable. This article discusses the preliminary evidence from research on mice. Mice that were genetically modified to have this specific mutation developed ADHD symptoms. When given stimulant medication, the symptoms decreased.http://www.webmd.com/add-adhd/news/20110418/adhd-genetic-mutation-may-be-key