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 treatments.
The children were unable to hear because of inherited genetic mutations that disrupt the body’s ability to make a protein necessary for auditory signals to travel seamlessly from the ear to the brain.
Doctors at Fudan University in Shanghai treated the children, aged between one and 11, on both ears in the hope that they would regain enough 3D hearing to participate in conversations and figure out which direction sounds came from.
Within weeks of receiving the therapy, the children had regained their hearing, could locate the sources of sounds, and recognized 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 study, said the results were “stunning,” adding that researchers “dramatically progressive” continued to see.
The therapy uses an inactive virus to smuggle working copies of the affected gene, Otof, into the inner ear. Once inside, the cells in the ear use the new genetic material as a template to produce 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 thirteen weeks, while he responded to neither before receiving the injections.
Another patient, a three-year-old girl, does not respond to sounds, but can understand sentences and speak some words thirteen weeks after treatment.
The oldest patient, an eleven-year-old girl, did not respond to tones played at different pitches before therapy, but six weeks later responded to all tones and was able to participate in speech training from the thirteenth week.
More than 430 million people worldwide suffer from disabling hearing loss, of which approximately 26 million are deaf from birth.
Up to 60% of deafness in children is due to genetic factors. The children in the trial have a condition called DFNB9, caused by Otof mutations, which is responsible for 2-8% of all congenital hearing loss.
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In January, the same US-Chinese team reported subsequent improvements treating children who are deaf in one ear, but the intention was always to restore hearing in both ears. Being able to hear in both ears helps the children figure out where sounds are coming from, an ability that is important for everyday situations such as talking in groups and being aware of traffic when crossing the road, the researchers said.
Larger studies will be needed to assess 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 in surgery. Treating both ears also increases the risk of a stronger immune response, which is caused when the body’s defenses respond to the virus the therapy delivers.
“Our hope is that this research can be expanded and that this approach can also be explored for deafness caused by other genes or non-genetic causes,” Chen said. “Our ultimate goal is to help people regain their 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 lead researcher on that study, said the therapy marked a new era in the treatment of deafness.