Michael Wigler, a professor of genomics at Cold Spring Harbor Laboratory (CSHL) in Long Island, N.Y., and senior author of the new model described in Proceedings of the National Academy of Sciences USA has performed an exhaustive analysis of risk based on a database of families with more than one autistic child. (The Autism Genetic Resource Exchange, or AGRE, manages the database). His team determined that most cases of autism arise from novel, spontaneous mutations passed down from one or both parents, resulting in large gaps in a person's genome often encompassing several genes, which are then disrupted or inactivated. (This loss of genetic code—known as copy number variation—results in an offspring receiving only one of the standard two copies of a gene, which could cause an insufficient amount of protein to be produced by those genes.) In most instances, this mutation will result in an autistic child. However, in some cases—more likely in girls than boys—the recipient of this mutation will not produce any symptoms.