2024-01-26 11:06:29
Gene therapy has allowed several children born with hereditary deafness to hear for the first time.
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A study published Wednesday reportssignificant improvement in hearing in five of six children treated in China.
On Tuesday, Children’s Hospital of Philadelphia announced similar improvements in an 11-year-old boy being treated there. And earlier this month, Chinese researchers published a study showing equivalent results in two other children.
So far, experimental therapies target only one type of hereditary deafness.
But scientists say similar treatments might one day help many more children with other types of genetically caused deafness. In the world, 34 million children have deafness or hearing loss, and genes are responsible for almost 60% of cases.
Hereditary deafness is the latest condition that scientists are targeting with gene therapy, which is already approved to treat diseases such as sickle cell anemia and severe hemophilia.
Children with hereditary deafness often receive a device called a cochlear implant that helps them hear sounds.
“No treatment was able to reverse hearing loss… This is why we have always tried to develop therapy“says Zheng-Yi Chen of Massachusetts Eye and Ear in Boston, one of the lead authors of the study published Wednesday in the journal Lancet.”We mightn’t be happier and excited regarding the results“.
The team filmed the patients’ progress in videos. One of them shows a baby, who previously might not hear at all, turning around in response to a doctor’s words, six weeks following treatment. Another shows a little girl who, 13 weeks following treatment, hears and repeats words such as “father”, “mother”, “grandmother”, “sister” and “I love you”.
How does therapy work?
All the children participating in the experiments suffer from a disease which represents 2 to 8% of cases of hereditary deafness.
It is caused by mutations in a gene responsible for an inner ear protein called otoferlin, which helps hair cells transmit sound to the brain. The therapy delivers a functional copy of this gene into the inner ear during surgery. Most children were treated in only one ear, except for one child who was treated in both ears.
The study of six children was conducted at Fudan University in Shanghai, under the direction of Dr. Yilai Shu, who trained in the laboratory of Zheng-Yi Chen, who collaborated on the research. Funding came from several Chinese scientific organizations and biotechnology company Shanghai Refreshgene Therapeutics.
The researchers observed the children for regarding six months. They don’t know why the treatment didn’t work for one of them. But the other five, who previously suffered from total deafness, can now hear normal conversation and speak with other people. Zheng-Yi Chen estimates that they now hear at a level between 60 and 70 percent of normal. The therapy did not cause any major side effects.
Dramatic improvement in hearing
Preliminary results from other research are equally positive.
Regeneron Pharmaceuticals of New York announced in October thata child under two years old who participated in a study sponsored by the company Decibel Therapeutics saw his hearing improve six weeks following gene therapy.
The Philadelphia hospital – one of several sites participating in a trial sponsored by a subsidiary of the pharmaceutical company Eli Lilly called Akouos – reported that its patient, Aissam Dam, originally from Spain, was hearing sounds for the first time times following being treated in October. Although they are muffled as if he were wearing foam earplugs, he is now able to hear his father’s voice and cars on the road, says Dr. John Germiller, who led the research at Philadelphia.
“This is a dramatic improvement“, he adds.
“His hearing went from a state of complete and profound deafness, without any sound, to a level of mild to moderate hearing loss, which can be considered a mild disability. It’s exciting for us and for everyone“.
Dr. Lawrence Lustig of Columbia University, who is participating in the Regeneron trial, says that if children in these studies do not acquire perfect hearing, “even recovery from moderate hearing loss in these children is quite astounding“.
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However, he adds that many questions remain, such as the lifespan of therapies and the continued improvement of hearing in children.
Furthermore, some people consider that gene therapy for deafness poses ethical problems.
Teresa Blankmeyer Burke, professor of deaf philosophy and bioethicist at Gallaudet University, said in an email thatthere is no consensus on the need for gene therapy targeting deafness.
She also emphasizes that deafness does not cause serious or fatal diseases such as, for example, sickle cell anemia. She adds that it is important to consult members of the deaf community on prioritizing gene therapy, “particularly because many perceive it as a potential threat to the thriving of deaf communities that use sign language“.
In the meantime, the researchers said their work is moving forward.
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“This is real proof of the effectiveness of gene therapy“, conclut Zheng-Yi Chen, “which opens the way to the entire field“.
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