by Gene therapy has enabled some children born with hereditary deafness to hear.
A small study published Wednesday documents significant restoration of hearing in five of six children treated in China. On Tuesday, the Children’s Hospital of Philadelphia announced similar improvements in an 11-year-old boy treated there. And earlier this month, Chinese researchers published a study that showed much the same in two other children.
So far, the experimental therapies only focus on one rare condition. But scientists say similar treatments could one day help more children with other types of deafness caused by genes. Worldwide, 34 million children have deafness or hearing loss, with genes responsible for up to 60% of cases. Hereditary deafness is the latest condition scientists are targeting with gene therapy, which is already approved to treat illnesses such as sickle cell disease and severe hemophilia.
Children with hereditary deafness often receive a device called a cochlear implant that helps them hear sound.
“No treatment could reverse hearing loss … That’s why we’ve always wanted to develop a therapy,” said Zheng-Yi Chen of Boston’s Mass Eye and Ear, senior author of the study published Wednesday in the journal Lancet. “We couldn’t be happier or more excited about the results.”
The staff captured the patients’ progress in videos. One shows a child, previously unable to hear at all, looking back in response to a doctor’s words six weeks after treatment. Another shows a little girl 13 weeks after treatment repeating father, mother, grandmother, sister and “I love you.”
All the children in the experiments have a condition that accounts for 2% to 8% of hereditary deafness. It is caused by mutations in a gene responsible for a protein in the inner ear called otoferlin, which helps hair cells transmit sound to the brain. The one-time therapy delivers a functional copy of that gene to the inner ear during a surgical procedure. Most of the children were treated in one ear, although one child in the pair study was treated in both ears.
The study was conducted with six children at Fudan University in Shanghai, led by Dr. Yilai Shu, who trained in Chen’s lab, collaborated on the research. Funders include Chinese scientific organizations and biotechnology company Shanghai Refreshgene Therapeutics.
Researchers observed the babies for about six months. They don’t know why the treatment didn’t work in one of them. But the other five, who were previously completely deaf, can now hear regular conversation and talk to others. Chen estimates that they now hear at a level of about 60% to 70% of normal. No major side effects occurred with the therapy.
Preliminary results from other research were equally positive. New York’s Regeneron Pharmaceuticals announced in October that a child under 2 in a study they sponsored with Decibel Therapeutics showed improvements six weeks after gene therapy. The Philadelphia hospital – one of several sites in a test sponsored by an Eli Lilly subsidiary called Akouos – reported that their patient, Aissam Dam of Spain, heard sounds for the first time after receiving treatment in October. Although they are muffled because he is wearing foam earplugs, he is now able to hear his father’s voice and cars on the road, said Dr. John Germiller, who led the research in Philadelphia.
“It was a big improvement,” Germiller said. “His hearing is improved from a state of complete and profound deafness with no sound at all to a level of mild to moderate hearing loss, which you can say is a mild disability. And that is very exciting for us and for everyone. “
Dr. Lawrence Lustig of Columbia University, who is involved in the Regeneron trial, said that while the children in these studies do not have perfect hearing, “even moderate hearing recovery in these children is remarkable.”
Still, he said, many questions remain, such as how long the therapies will last and whether the children’s hearing will improve.
Also, gene therapy for deafness is considered an ethical problem by some. Teresa Blankmeyer Burke, a deaf philosophy professor and bioethicist at Gallaudet University, said in an email that there is no consensus about the need for gene therapy targeting the deaf. She also pointed out that deafness does not cause severe or fatal illness, for example, sickle cell disease. She said it’s important to reach out to members of the Deaf community about prioritizing gene therapy, “especially since many see this as an existential threat to the flourishing of Deaf signing communities.”
Meanwhile, researchers said their work is continuing.
“This is real proof that gene therapy is working,” Chen said. “It opens up the whole field.”
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The Associated Press Health and Science Section is supported by the Howard Hughes Medical Institute Science and Media Education Group. The AP is solely responsible for all matters.
