Five children born deaf have had their hearing restored in both ears after taking part in an “amazing” gene therapy trial that is raising hopes for further treatment.
The children were unable to hear because of inherited genetic mutations that disrupt the body’s ability to make a protein needed to ensure that auditory signals travel seamlessly from the ear to the brain.
Doctors at Fudan University in Shanghai treated the children, aged between one and 11, in both ears in the hope that they would regain enough 3D hearing to participate in conversations and figure out which direction sounds were coming from.
Within weeks of receiving the therapy, the children regained hearing, were able to locate the sources of sounds and recognize speech in noisy environments. Two of the children were recorded dancing to music, the researchers reported Naturopathy.
Dr. Zheng-Yi Chen, a scientist at Massachusetts Eye and Ear, a Harvard teaching hospital in Boston who co-led the trial, said the results were “amazing,” adding that researchers were still seeing how the children’s hearing ability ” progress dramatically”.
The therapy uses an inactive virus to smuggle working copies of the affected gene, Otof, into the inner ear. Once inside, cells in the ear use the new genetic material as a template to remove working copies of the crucial protein, otoferlin.
Video footage of the patients shows a two-year-old boy responding to his name three weeks after treatment and dancing to music after 13 weeks, after showing no response to either before receiving the injections.
Another patient, a three-year-old girl, does not respond to sounds, but can understand sentences and speak some words 13 weeks after the treatment.
The oldest patient, an 11-year-old girl, showed no response to tones played at different pitches before therapy, but responded to all six weeks later and was able to participate in speech training from the 13-week mark.
More than 430 million people worldwide are affected by disabling hearing loss, of which approximately 26 million are deaf from birth.
Up to 60% of childhood deafness is due to genetic factors. The children in the trial have a condition called DFNB9, caused by Otof mutations, which accounts for 2-8% of all congenital hearing loss.
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In January, the same American-Chinese team reported improvements treating the deaf children in one ear, but the intention was always to restore hearing in both ears. If they can hear in both ears, the children can work out where sounds are coming from, an ability important for everyday situations such as speaking in groups and being aware of traffic when crossing the road, the researchers said.
It will take larger trials to determine the benefits and risks of the therapy in more detail. The gene therapy is injected during a minimally invasive surgical procedure, so treating both ears doubles the time patients spend on surgery. Treating both ears also increases the risk of a stronger immune response, which is caused when the body’s defenses react to the virus delivering the therapy.
“Our hope is that this trial can expand and this approach can also be looked at for deafness caused by other genes or non-genetic causes,” Chen said. “Our ultimate goal is to help people regain hearing, regardless of how their hearing loss was caused.”
Last month, a British toddler became the first person to have her hearing restored in one ear after receiving a similar gene therapy for hearing loss caused by Otof mutations.
Prof Manohar Bance, the principal investigator of that trial, said the therapy had worked a new era in the treatment of deafness.
