Mice bred to lack a crucial brain gene show many of the characteristics of autism, say US scientists based at the University of Texas. The team created a 'knockout' mouse that is missing a gene called Pten, specifically in areas of the brain associated with learning and memory. The study, reported in the journal Neuron, may shed light on the biological basis of this poorly understood disorder.
Autism - along with several related conditions together known as autistic spectrum disorders - is a lifelong developmental disability that typically appears during the first three years of life. The disorder affects social and language skills, and the way in which a child relates to people, objects and events. Autism often runs in families, suggesting that it has a genetic basis, although it is thought that the combined effects of at least ten different genes are involved.
Previous research has linked the Pten gene to some brain disorders, but mice completely missing the gene show a broad range of different symptoms. In the latest study, the scientists created mice that only lack the Pten gene in cells that make up the cerebral cortex and hippocampus areas of the animal's brain - the parts associated with learning and memory respectively. They found that the mice had autistic traits such as poor social interaction and high sensitivity.
The animals were far less curious about new mice entering the cage than their normal littermates. The altered mice also showed the same level of interest in an empty cage as one containing another mouse - a finding that reflects the behaviour of children with autistic spectrum disorders. In addition, they were less likely to build nests or look after their young, and were more sensitive to stressful events such as being picked up, or subjected to loud noises.
Team leader Luis Parada told BBC News Online that 'it would be really exciting if it turned out that we've zeroed in on the anatomical regions where things go wrong in autistic patients, regardless of how the autism occurs'. In an accompanying comment piece, Anthony Wynshaw-Boris and Joy Greer, of the University of California, call the findings 'intriguing', but caution that the research does not provide the complete picture. They say that other features typical of autistic spectrum disorders, such as repetitive behaviour, are not present in the altered mice.
UK autism expert Simon Baron Cohen, of Cambridge University, told BBC News Online that the mouse behaviour mirrored that of a sub-group of people with autistic spectrum disorder, but added that 'social abnormalities in a mouse may be caused by very different factors to human social abnormalities'. He said that further research was needed, to see if the human version of Pten is involved in susceptibility to the condition.
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