Previous studies have shown that susceptibility to autism can be influenced by large chunks of DNA which are sometimes found to be deleted or duplicated on patient's chromosomes (see previous news feature). An international study published in the January 2011 issue of the Journal of Medical Genetics and led by scientists from the Wellcome Trust Centre for Human Genetics describes in detail two families with 1.6/1.8 million letters of DNA missing from chromosome 16. In one of these families, the deletion is present in all three children with autism, but is not seen in their 4 unaffected siblings.
Usually deletions of this size would disrupt many genes, making it difficult to work out which one is relevant. However, in this case the deletions lie in a "gene desert" - a region of chromosome 16 that does not contain many genes - and so only a single gene called cadherin 8 is implicated. Deletions of this gene have never been described previously in studies involving unaffected populations.
In collaboration with the Human Developmental Biology Resource, the scientists go on to show that the gene is turned on in brain regions critical to development of the cerebral cortex. Interestingly, a shorter version of this gene is turned on more strongly towards the front of the brain.
For more information, see: Rare familial 16q21 microdeletions under a linkage peak implicate cadherin 8 (CDH8) in susceptibility to autism and learning disability. Pagnamenta A.T., Khan H., Walker S., et al. Journal of Medical Genetics, Genet 2011 48: 48-54 (Editor's Choice) - click here.