Autism :: Genetic mutation in autism identified

A gene called SHANK3 is mutated in a small number of individuals with autism, providing new insight into the biological basis of this disease, according to a study to be published in the January issue of Nature Genetics.

Autism spectrum disorders (ASD), which comprise a range of disorders affecting social interaction and communication, affect 6 out of every 1,000 children. Approximately 3-6% of cases are caused by chromosomal rearrangements, with a small region on chromosome 22 affected frequently in individuals with cognitive deficits accompanied by autistic behavior. This region contains three genes, one of which ? SHANK3 ? is a good candidate to be associated with autism given its expression in neuronal synapses.

Thomas Bourgeron and colleagues sequenced SHANK3 in more than 200 individuals with ASD, and found mutations in 3 families. An individual in one family had a significant deletion in the gene, while two brothers in a second family had a smaller deletion. In the third family, a girl with autism had a deletion in SHANK3, while her brother, affected with a mild form of autism called Asperger syndrome, had an additional copy of SHANK3. The protein encoded by SHANK3 interacts with other proteins called neuroligins, which have a role in neuronal signaling. Mutations in two of the genes encoding neuroligins have previously been found in a small number of individuals with autism, suggesting that neuroligin function should receive increased attention in the search for the biological basis of ASD.

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