Scientists have been able to prevent a form of inherited deafness from developing in mice by editing their genes. The technique, while still in its early stages, lays the groundwork for a potential treatment that can help prevent hearing loss in children who inherited the condition from their parents.
“We’re hopeful that our results will help guide the development of such strategies,” says David Liu, a genetic engineer at Broad Institute, the Massachusetts Institute of Technology and Harvard University.
The experiments so far have been performed on a type of mouse known as a Beethoven mouse. Liu considered these mice to be perfect candidates because they carry a defect than causes them to lose their hearing starting early in life. The defect is known to cause deafness in people as well.
Liu claims that people who are born with even one bad copy of this gene lose their hearing ability starting from early childhood. Once they reach late childhood “they’re profoundly deaf”, according to the genetic engineer.
The gene-editing technique is known as CRISPR Cas-9 and was used by Liu to eliminate the defective gene. This gene is responsible for destroying tiny hairs inside the ear which are needed for normal hearing. Liu opted to inject the gene-editor into the ears of Beethoven mice one day after they were born.
According to Liu, once the gene-editor is inside the ear, it targets the defective gene and cuts the DNA, essentially preventing the hair cells from dying.
The Beethoven mice have a second, healthy variant of the required gene which prompted Liu to see if by eliminating the mutant gene, the mice would be allowed to develop hearing capacity.
One month later, when Liu treated the mice a second time, the subjects appeared to hear much better than before they had their ears edited.
The treated ears were able to hear quiet or “normal quiet” conversations while the uninjected ears required sounds that were “about as loud as a garbage disposal” for them to register a response.
Liu claims that similar gene-editing approaches could be developed to prevent deafness in babies born with the same defect, or even other inherited mutations that cause hearing loss.
The findings were published in the journal, Nature.
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