Two children who were born deaf can now hear and dance to music after undergoing innovative gene therapy.
The treatment, which is given as an infusion into the ear, works by replacing defective DNA that causes a type of inherited deafness known as DFNB9.
Researchers hope that a similar approach could help in other congenital cases of deafness, which account for 60 percent of the 430 million cases worldwide.
In the world’s first gene therapy trial, five children in China (two girls and three boys, all around three years old) gained hearing in both ears. All five were able to hear and speak words and locate where a sound was coming from.
The treatment, which is given as an infusion into the ear, works by replacing defective DNA that causes a type of inherited deafness known as DFNB9. Dr. Yilai Shu of Fudan University Eye and ENT Hospital examines a young patient
The DFNB9 deafness strain is caused by a failure in the production of a protein known as otoferlin.
But two showed more advanced improvements and were even able to respond to music, which has more complex sound signals.
The latest results, published in Nature Medicine, build on work the team carried out two years ago when they treated children in one ear.
After gene therapy, the young people went from being profoundly deaf to having mild to moderate hearing loss in the treated ear. But giving the therapy to both ears had additional benefits compared to the previous trial, the team said, including the ability to hear in noisy environments.
The DFNB9 strain of deafness is caused by a failure in the production of a protein known as otoferlin, which is necessary for the transmission of sound signals from the ear to the brain. Currently, a cochlear implant is the only effective treatment for patients.
For the trial, researchers at Fudan University Eye and Ear Hospital in Shanghai used a modified version of the adeno-associated virus (AAV), which is not harmful to humans, to deliver the genes.
After gene therapy, the young people went from being profoundly deaf to having mild to moderate hearing loss in the treated ear (file photo)
Lead author of the study, Professor Zheng-Yi Chen, said: “The results of these studies are surprising.
“We continue to see the hearing ability of treated children progress dramatically and the new study shows additional benefits of gene therapy when administered to both ears, including improvements in speech recognition in noisy environments.”
Professor Chen, who is also an associate professor of otolaryngology (head and neck surgery) at Harvard Medical School, added: “Our ultimate goal is to help people regain their hearing, regardless of the cause of your hearing loss.
It comes six months after a girl in the UK received a similar type of gene therapy in a trial at Addenbrooke’s Hospital in Cambridge. Opal Sandy, 18 months, from Oxfordshire, received the treatment in her right ear, while she had a cochlear implant in her left ear.
After a few weeks, he was able to hear loud sounds, like clapping, and now he can hear soft sounds, like a whisper, and is starting to say words like “mom,” “dad,” and “uh oh.”
‘The results are surprising’