Gene therapy has allowed many children born with hereditary deafness to hear.
A small study published Wednesday documented significant improvement in hearing in five out of six children treated in China. On Tuesday, the Children’s Hospital of Philadelphia announced similar developments in an 11-year-old boy being treated there. And earlier this month, Chinese researchers published a study showing much the same thing in two other children.
So far, experimental treatments target only a single rare condition. But scientists say similar treatments could one day help many more children suffering from other types of deafness caused by genes. 34 million children worldwide have deafness or hearing loss, and genes are responsible for 60% of cases. Hereditary deafness is the latest disorder scientists are targeting with gene therapy, which has already been approved to treat diseases such as sickle cell disease and severe hemophilia.
Children with hereditary deafness often receive a device called a cochlear implant that helps them hear sounds.
“No treatment can reverse hearing loss… So we were always trying to develop a therapy,” said Zheng-Yi Chen of Boston Mass Eye and Ear, a senior author of the study published Wednesday in the journal Lancet. “We couldn’t be happier and more excited about the results.”
The team recorded the patients’ progress with videos. In one of the photos, a baby who had never been able to hear before was seen looking back in response to the doctor’s words, six weeks after treatment. Another shows a little girl 13 weeks after treatment repeating the words “I love you” to her father, mother, grandmother, and sister.
All children in the trials had a condition that accounts for 2% to 8% of hereditary deafness. It is caused by mutations in the gene responsible for the inner ear protein called otoferlin, which helps hair cells transmit sound to the brain. The one-time therapy delivers a functional copy of this gene to the inner ear during a surgical procedure. Most of the children had one ear treated, but one child in the two-person study had both ears treated.
The study, conducted with six children, was conducted by Dr. Chen, who trained in Chen’s laboratory and collaborated on the research. It was held at Fudan University in Shanghai, under the leadership of Yilai Shu. Funders include Chinese science organizations and biotechnology company Shanghai Refreshgene Therapeutics.
Researchers observed the children for about six months. They don’t know why treatment didn’t work for one of them. But the other five people, who were previously completely deaf, can now hear normal conversations and talk to others. Chen estimates that they now hear at around 60% to 70% of normal. The therapy did not cause any significant side effects.
Preliminary results from other studies were equally positive. Regeneron Pharmaceuticals in New York announced in October that a child under age 2 showed improvement six weeks after gene therapy in a study sponsored by Decibel Therapeutics. The Philadelphia hospital, one of several sites in the test sponsored by Eli Lilly’s Akouos subsidiary, reported hearing voices for the first time after their patient, Aissam Dam from Spain, received treatment in October. Dr., who led the research in Philadelphia. John Germiller said he can now hear his father’s voice and the cars on the road, although they are muffled as if he were wearing foam earplugs.
“This was a dramatic development,” Germiller said. “His hearing has improved from complete and profound deafness with no sound at all to mild to moderate hearing loss, which you might call a mild disability. This is very exciting for us and everyone. ”
Dr. from Columbia University, who took part in the Regeneron research. Although the children in these studies did not have perfect hearing, “even moderate improvement of hearing loss in these children is quite surprising,” said Lawrence Lustig.
Still, he added, many questions remain, such as how long the therapies will last and whether children’s hearing will continue to improve.
Some people also think gene therapy for deafness is ethically problematic. Teresa Blankmeyer Burke, a deaf philosophy professor and bioethicist at Gallaudet University, said in an email that there is no consensus on the need for gene therapy targeting deafness. She also noted that deafness does not cause serious or fatal diseases such as sickle cell disease. He said it was important to engage with members of the deaf community about prioritizing gene therapy; “in particular, this is perceived by many as a potentially existential threat to the development of Deaf communities.”
Meanwhile, the researchers said their work is progressing.
“This is real evidence that gene therapy works,” Chen said. “It opens up the whole space.”
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