Protein in brain triggers autism

Autism is a disorder which, to varying degrees, affects the ability of children and adults to communicate and interact socially. While hundreds of genes linked to it have been found, the precise combination of genetics, biochemistry and environmental factors producing autism is still unclear. Now, an international team led by Duke University has found “Shank3” protein plays a key role in triggering autistic spectrum disorders. The protein is found in the synapses — the junctions between brain cells (neurons).

The scientists have based their findings on an analysis on autistic mice. They created rodents which had a mutated form of Shank3, and found these animals avoided social interactions with other mice.

They also engaged in repetitious and self-injurious grooming behaviour.

When the team analysed the animals’ brains they found defects in the circuits that connect two different areas of the brain, the cortex and the striatum. Healthy links between these areas are thought to be key to effective regulation of social behaviours and social interaction. The scientists say their work underscores just what an important role Shank3 plays in the establishment of circuits in the brain which underlie all our behaviours. Lead researcher Dr Guoping Feng was quoted by the ‘BBC’ as saying, “Our study demonstrated that Shank3 mutation in mice lead to defects in neuron-neuron communications.

“These findings and the mouse model now allow us to figure out the precise neural circuit defects responsible for these abnormal behaviours, which could lead to novel strategies and targets for developing treatment.”

It is thought that only a small percentage of people with autism have mutations in Shank3, but Dr Feng believes that many other cases may be linked to disruptions to other proteins that control synaptic function. Carol Povey, director of the National Autistic Society’s Centre for Autism, added: “Animal research can help advance our understanding or the role of genetics and their influence on behaviour, however it is only a small part of the picture when it comes to understanding autism.

“Human brains are far more complex than those of other mammals, and it is believed that a variety of factors are responsible for the development of the condition.”