A treatment for fragile X may be on the horizon

Illustration of formula

Fragile X got its name because under a microscope, a portion of the X chromosome appears “broken” or “fragile.” Fragile X syndrome is the most common cause of inherited mental impairment. 

Emory researchers are testing what may be the first drug therapy intended to address the complex learning and behavior problems associated with fragile X syndrome.

Fragile X syndrome is caused by a genetic mutation that inhibits the production of the protein FMRP, which regulates the amount of other proteins produced in the brain. The absence of FMRP leads the glutamate receptor mGluR5 to trigger the overproduction of synaptic proteins, resulting in the learning and behavior problems characteristic of fragile X.

“The drug we are testing is an mGluR5 antagonist, which puts a brake on the mGluR5 activity,” says Emory geneticist Jeannie Visootsak, principal investigator of the study. “In mouse and fruit fly models, we were able to improve cognition with this antagonist.”

The gene for fragile X was discovered in 1991 by Emory human genetics chair Stephen Warren. He led a team that discovered the mutated gene on the X chromosome, and later that year, another Emory team helped develop a screening test.

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Emory Medicine Summer 2010