A new study has shown life-changing gene therapy can reverse deafness in people born with complete or severe hearing loss from babies to adults.
More than 50% of cases of deafness present from birth, also known as congenital deafness, are genetic and treatments typically rely on hearing aids and cochlear implants. These devices improve audibility but do not “fix” the defects in the ear that cause deafness, and can also be uncomfortable to wear. Researchers have been investigating treatments to reverse genetic defects causing deafness for years, and now, it has finally paid off.
Scientists led by Dr Maoli Duan at Karolinska Institutet in Sweden collaborated with hospitals and universities in China to successfully treat ten patients, improving all their hearing. “This is a huge step forward in the genetic treatment of deafness, one that can be life-changing for children and adults,” said Duan in a press statement.
All patients had genetic mutations in a gene called OTOF – this mutation prevents the body from producing a protein, called otoferlin, needed for transmitting sound signals from the inner ear to the brain. Evidently, the scientists used only a single injection of an adeno-associated virus, which is a highly tested and safe method for gene therapies, to deliver a healthy, working version of the OTOF gene into a thin membrane at the base of the cochlea called the round window.
Results were rapid, with some patients regaining hearing within just a month. Remarkably, after six months, all patients showed distinct improvement. Their hearing improved from 52 to 106 decibels – up to the sound of a chainsaw.
This study was conducted within a broad age range, from toddlers to adults. Children were seen to have the biggest responses, with one seven-year-old girl regaining almost all her hearing and ability to function normally with day-to-day conversations after just four months. In China, positive results like these have been seen in children before. However, this is the first time this treatment has been tested and successful in teenagers and adults.
Gene therapy can sound daunting and scary, especially when injections are mentioned. However, this treatment was well tolerated and safe. No serious adverse reactions were observed in the 6 to 12 months check-ups, carrying potential for near future medical applications on more patients.
But this is just one genetic mutation, what about others? “OTOF is just the beginning,” Duan stated. “We and other researchers are expanding our work to other, more common [mutations in] genes that cause deafness, such as GJB2 and TMC1 (mutations that also disrupt inner ear-to-brain communication).” Although these mutations are more complex, studies on animals have come back promising, with hope for successful treatment in patients in the future. This forges a new era of restorative medicine for people with deafness, and paves way for prosthetic devices to be a thing of the past, ultimately improving quality of life.
And the cherry on top? It means the chance to listen to Hans Zimmer’s Time and Cornfield Chase for the first time.
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