Dr. Buxbaum and his colleagues conducted a systematic screening of a region in which 411 families have members with autism or autistic disorder. It was found that the genetic variations in one gene that occur with greater frequency in individuals with autism disease and their family members. This gene codes for a protein that is involved in production of ATP, the molecule that acts as fuel providing the energy cells need to function. Dysfunction of this gene could lead to irregularities in the production of molecules that fuel the cells. Since brain cells consume large amounts of energy even minor disruptions in production of such fuel can significantly affect the cells ability to function normally.