Thursday, March 22, 2012

Gene-induced brain changes can cause autism

Autism is a developmental disorder with a wide range of symptoms. Most people suffering from it struggle in coping with social interaction. Additionally, those who have acquired a more severe form of autism can also display other symptoms such as behaving in a repetitive way. We know the cause is largely genetic, and that makes for an early age onset, often in kids just three years old. Scientists have previously shown that faulty wiring in the brain is one of the most important underlying causes. In addition, a large set of candidate genes have been discovered: these are likely to play a role in altering normal brain physiology. How it all fits together is unknown, but scientists from the Medical College of Wisconsin discovered how a particular gene can cause brain changes.

During their experiments, a large number of volunteers were placed in a scanner. They got their brains scanned with fMRI, a technique commonly used to assess brain functionality. Utilizing the brain scanning technique, the scientists aimed to find out what happens if someone possesses a common variant of a particular gene called Cntnap2. Previous research has implied this gene in autism, but it is not yet clear what it does exactly.

After analysing the brains of 328 participants, scans revealed that the alleged risk factor causes several changes in how the brain is wired. It appears the Cntnap2 variant causes changes in how various brain areas connect with each other. Additionally, communication between brain cells seems to be altered. The scientists think these changes can result in symptoms such as the ones found in autism. As they were able to exclude common confounding factors such as thickness of brain fibres, it is likely the differences can be attributed to Cntnap2.

As said, it is already known that underlying factors of autism are largely genetic. We have found a large set of genes with possible implications, but their exact role is unclear. Additionally, we already know there is something wrong with the wiring of the brain if we look at it in a physiological way: it appears as if a common change in the structure of the Cntnap2 gene can provide an explanation, although there are many other factors involved. It is also known that changes in Cntnap2 do not necessarily result in autism. Equally so, changes in this particular gene are not necessary for autism to develop at all. Nevertheless, because Cntnap2 changes appear to fit physiological evidence previously found in patients, it tells us a great deal about the biological foundation of autism. 

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