Genetic studies have identified several loci, or stretches of chromosomal DNA, that are defective in individuals with autism. These loci contain more than one gene, so the next step is to identify the specific genes that are mutated. To that end, Alea Mills and her colleagues at Cold Spring Harbor Laboratory in New York propose to develop a series of mouse models carrying chromosomal defects analogous to those seen in individuals with autism.

Numerous genes have been linked to autism, but it is not entirely clear how mutations in individual genes translate to the social deficits seen in people with the disorder. Because the symptoms of autism typically appear during periods of heavy neural development, Mriganka Sur at the Massachusetts Institute of Technology suggests that defects in genes that control early brain development are partly to blame.

The genetics of autism has proven to be as complex as the genetics of other diseases in people. As seen in many human diseases, candidate genes appear to affect a wide range of biological processes, but not very consistently.