• Posted January 25, 2024

Gene Therapy Brings Hearing to Kids With Congenital Deafness

Five of six Chinese children born deaf due to a rare genetic defect now have the ability to hear, thanks to an experimental gene therapy.

The therapy involved a hollowed-out virus loaded with a healthy version of the gene responsible for producing otoferlin, a protein necessary for the transmission of sound signals from the inner ear to the brain.

Doctors injected the virus into the inner ears of the children through a special surgical procedure, and five of the kids experienced hearing recovery within six months.

“The results from this study are truly remarkable. We saw the hearing ability of children improve dramatically week by week, as well as the regaining of their speech,” said researcher Zheng-Yi Chen, an associate scientist in Eaton-Peabody Laboratories at Harvard-affiliated Mass Eye and Ear in Boston.

Mass Eye and Ear researchers worked with doctors in China to treat the six children, with the trial taking place at the Eye & ENT Hospital of Fudan University in Shanghai.

These results bolster findings from a U.S.-based trial that cured otoferlin deafness in an 11-year-old Moroccan boy being treated at the Children's Hospital of Philadelphia.

The Chinese trial treated its first patient more than a year ago, in December 2022, and thus represents the first human clinical trial to administer gene therapy for otoferlin deafness, researchers said.

The Moroccan boy received his gene therapy in October in one ear. Within four months, his hearing improved enough that he now has only mild to moderate hearing loss in the treated ear, according to a CHOP news release.

“There's no sound I don't like,” patient Aissam Dam told the New York Times through an interpreter. “They're all good.”

About one in 500 infants are born with or develop hearing loss during early childhood, according to the U.S. Centers for Disease Control and Prevention.

More than 60% of hearing loss cases in children stem from genetic reasons, researchers said in background notes. Mutation of the otoferlin gene is one of those reasons for congenital deafness.

But because this condition is caused by a lack of the signaling protein, researchers had hoped it could be reversed with gene therapy.

About 200,000 people around the world are affected by otoferlin deafness, the Times reported.

All six children in the Chinese study had total deafness due to their otoferlin mutation, researchers said.

Within a half-year of treatment, five of the kids had demonstrated hearing recovery, dramatic improvements in their speech perception, and a restored ability to conduct normal conversation.

The treatment also produced no major side effects in the children, researchers said.

Researchers next plan to expand the trial to a larger sample size, and continue tracking treated kids to see how well they do.

“Not since cochlear implants were invented 60 years ago, has there been an effective treatment for deafness,” Chen said in a hospital news release. “This is a huge milestone that symbolizes a new era in the fight against all types of hearing loss.”

The new study was published Jan. 24 in The Lancet journal.

Researchers from both the United States and Chinese trials plan to present their findings early next month at the annual meeting of the Association for Research in Otolaryngology.

More information

The U.S. Centers for Disease Control and Prevention have more about the genetics of hearing loss.

SOURCE: Mass Eye and Ear, news release, Jan. 24, 2024