Using family linkage studies, a genome scan, and a mouse model, researchers have triangulated onto a gene implicated in at least some cases of autism. Called WNT2, the gene is part of a family of genes that influences brain development. Found on the long arm of chromosome 7, WNT2 maps to an area highlighted as suspicious by earlier family linkage studies.
These suspicions were heightened when researchers found that in one individual with autism, WNT2 lies next to a broken piece of chromosome 7. They decided to look for mutations in the gene in 135 people with autism and their families. In two of the families, researchers found mutations. One parent and the autistic child carried the mutation, while none of the nonautistic siblings or controls carried it. Furthermore, mice bred without a gene essential to the functioning of WNT2 show diminished social interactions, like people with autism.
Vastag B. Brain Gene for Autism?. JAMA. 2001;285(23):2966. doi:10.1001/jama.285.23.2966-JHA10005-2-1