WASHINGTON: There is evidence now that a mutation of a gene called PTEN could be the cause of at least some forms of autism, the disease that affects human behavior.
Researchers at the University of Texas Southwestern Medical Center at Dallas said they have been able to create mice with autism features by deleting PTEN in certain parts of the brain.
Earlier studies have found that some people with autism have mutations in this gene, but it has not been possible to conclusively establish this has been the cause for the disorder.
The scientists deleted the gene from the front of the brain and from areas of the hippocampus, a structure involved in memory and other functions, of the mice and these mice were found to display characters resembling autism like oversensitivity to stimuli and deficits in social interaction. The mice also exhibited physical abnormalities in their brains.
Senior author of the study Dr Luis F Parada said in a statement that the exciting thing about the study is that it helped the scientists to "zero in on at least one anatomic location of abnormality, because we targeted the gene to very circumscribed regions of the brain."
The details of the study are published in the 4 May issue of Neuron.
The scientists found that compared to normal mice, the brains of the altered mice were noticeably different in the areas where PTEN was deleted. Nerve cells were thicker than normal and had a higher-than-normal number of connections to other nerve cells. This could well explain the problems connected with sensory overload.
The mice were found to be socially less skilled, less curious about, say a new mouse being put into the cage. They also showed the same level of interest in an empty cage and in one containing another mouse. These are almost like the behaviour of children with autistic spectrum disorders.
The genetically altered mice were more sensitive to stressful stimuli, such as loud noises or being picked up.
The scientists will now go into the next phase of the study by treating the altered mice with drugs to find out whether it is possible to reverse the condition.
