Researchers in Boston have used gene therapy to successfully restore hearing in deaf mice. They say that for humans, the research could one day make conventional deafness technologies like cochlear implants, unnecessary and obsolete. Ben Gruber reports.
STORY: In this lab at Boston Children's Hospital a cure for genetic deafness is taking shape. Lead researcher Jeff Holt says that if all goes as planned, children of the future who lose their ability to hear due to genetic mutation will never go deaf. Holt and his fellow researchers are attacking the problem at its source - they're using engineered viruses to repair damaged genes that make up parts of the inner ear. (SOUNDBITE) (English) JEFF HOLT, ASSOCIATE PROFESSOR, BOSTON CHILDREN'S HOSTPIAL, SAYING: "Our strategy was to take a viral vector, remove the viral genes so that it doesn't make anyone sick and to replace those with the correct DNA sequence for TMC1." TMC1 is a gene critical to hearing. It's responsible for encoding proteins that convert sound into electrical signals that the brain can process. To test their treatment protocol, Holt and his team used two types of deaf mice that model the dominant and recessive genetic mutations of TMC1 in humans. They delivered their engineered virus to the inner ears of the mice. (SOUNDBITE) (English) JEFF HOLT, ASSOCIATE PROFESSOR, BOSTON CHILDREN'S HOSTPIAL, SAYING: "We found that we can restore function in both cases for recessive and dominant forms of TMC1 mutations." While genetic testing and brain activity showed that their treatment worked, the researchers still needed to find out if the deaf mice could actually hear. (SOUNDBITE) (English) JEFF HOLT, ASSOCIATE PROFESSOR, BOSTON CHILDREN'S HOSTPIAL, SAYING: "We can't really ask a mouse if they are able to hear but we can play a loud sudden sound and a normal mouse will jump in response to that, a deaf mouse does not move at all but after our gene therapy treatment the deaf mice began to jump." Holt says there at least 70 different mutations that cause one in one thousand people do go deaf in adolescence. He says this gene therapy platform could potentially lead to treatment for all of them - ensuring that in the future no child ever loses their ability to hear.