Gene May Be Linked to Autism

A new study shows that a certain gene may be involved in autism.

The study, published in Neuron, doesn’t prove that that particular gene -- which is called the Pten gene -- causes autism. Many other genetic factors have also been linked to autism, the study also notes.

The study states that when researchers deleted the Pten gene in certain parts of mice’s brains, those mice showed some autism-like symptoms, including “abnormal social interaction and exaggerated responses to sensory stimuli.”

The Pten gene may be a “potential link to autism,” write the researchers. They included Chang-Hyuk Kwon, PhD, and Luis Parada, PhD, of the University of Texas Southwestern Medical Center at Dallas.

Kwon works at the university’s Center for Developmental Biology, which Parada directs. Parada also directs the university’s Kent Waldrep Center for Basic Research on Nerve Growth and Regeneration.

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Studying the Gene

The Pten gene suppresses tumors and has been noted in some people with autism, write Kwon and colleagues. People with Pten gene mutations “are prone to tumors,” the researchers write, and may display brain disorders including seizures and mental retardation.

Kwon’s team compared mice without the Pten gene with normal mice. In a university news release, Parada explains that by studying mice lacking the Pten gene, researchers can study specific parts of the brain where the Pten gene is found.

“In diseases where virtually nothing is known, any inroad that gets into at least the right cell or the right biochemical pathway is very important,” Parada says.

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Study’s Findings

Compared with normal mice, those lacking the Pten gene were:

Less social Hypersensitive to sensory stimuli, such as a startling noise Less interested in making nests when given nesting material More anxious in 2 out of 3 anxiety tests

Obviously, people don’t make nests and aren’t exactly like mice. However, the researchers saw some parallels between autism and some of the behavior of the mice lacking the Pten gene.

“We found that mutant mice exhibit a distinct pattern of behavioral abnormalities reminiscent of ASD [autism spectrum disorder],” write Kwon and colleagues. The researchers note that they don’t understand exactly what role the Pten gene may play in those behaviors.

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Study’s Details

To test sociability, the researchers presented a newcomer mouse and an empty cage to the mice. The normal mice were more interested in the newcomer mouse than the empty cage, but the mutant mice didn’t show the same preference.

In the anxiety tests, the researchers placed mice in an open space, maze, or boxes that were partly dark and partly lighted. The mice without the Pten gene acted more anxious in the open space and lingered longer in the dark part of the box than the other mice.

When the scientists studied the mice’s brains, they found thicker nerve cells and a higher-than-normal number of connections to other nerve cells in the brains of the mice lacking the Pten gene.

Those brain differences may lead to the sensory overload that people with autism develop, Parada notes in the news release.

The mice without the Pten gene didn’t show any problems with strength or the ability to move, the study also shows.

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By Miranda Hitti, reviewed by Louise Chang, MD

SOURCES: Kwon, C. Neuron, May 4, 2006; vol 50: pp 1-12. News release, University of Texas Southwestern Medical Center.