Five children born deaf have regained hearing in both ears after taking part in an “amazing” gene therapy trial, raising hopes for further treatments.
The children lost their hearing because they inherited a genetic mutation that blocks the production of a protein needed for auditory signals to travel smoothly from the ear to the brain.
Doctors at Shanghai’s Fudan University treated both ears of children between the ages of one and 11 in the hope of restoring enough 3D hearing to enable them to take part in conversations and determine which direction sounds were coming from.
Within a few weeks of treatment, the children regained their hearing, were able to localize sounds and recognize speech in noisy environments, and two children were videotaped dancing to music, the researchers reported. Nature Medicine.
Dr. Chen-Yi Chen, a scientist at Massachusetts Eye and Ear, a Harvard teaching hospital in Boston, who co-led the trial, said the results were “striking” and added that researchers continue to see “dramatic improvements” in the children’s hearing.
The treatment uses an inactive virus to smuggle a working copy of the affected gene, otoferin, into the inner ear. Once inside, the cells of the ear use the new genetic material as a template to produce large quantities of working copies of a key protein, otoferin.
Video footage of the patient showed a two-year-old boy who showed no reaction before the injection responding to his name three weeks after treatment and dancing to music 13 weeks later.
Another patient, a 3-year-old girl, was unable to respond to sounds but was able to understand sentences and speak a few words 13 weeks after treatment.
The oldest patient, an 11-year-old girl, showed no response to a range of pitches before treatment, but after 6 weeks she responded to all pitches and was able to participate in voice training sessions from the 13th week.
More than 430 million people worldwide suffer from hearing loss, of which approximately 26 million are born with hearing loss.
Up to 60% of childhood hearing loss is genetic. The children in this study have a condition called DFNB9, which is caused by a mutation in the otof gene and accounts for 2-8% of all cases of congenital hearing loss.
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In January, the same U.S.-China team Treatment of unilaterally deaf childrenBut restoring hearing in both ears has always been the aim, as hearing in both ears allows children to determine where sounds are coming from – a crucial ability for everyday life, such as talking in a group or watching traffic when crossing the street, the researchers said.
Larger trials will be needed to more fully evaluate the benefits and risks of this treatment. Because the gene therapy is injected during a minimally invasive surgical procedure, treating both ears doubles a patient’s surgery time. Treating both ears also increases the risk of a stronger immune response, triggered by the body’s defenses reacting to the virus that the treatment is administered against.
“We hope that this trial can be expanded so that this method can be applied to other genetic and non-genetic causes of hearing loss,” Chen says. “Our ultimate goal is to help people restore their hearing, whatever the cause of their hearing loss.”
Last month, a British toddler became the first person to have hearing restored in one ear after receiving a similar gene therapy for hearing loss caused by an Otov gene mutation.
Professor Manohar Bance, the trial’s lead investigator, said the treatment marked a new era in treating hearing loss.
