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• Posted June 5, 2024

Gene Therapy in Both Ears Restores Hearing to Babies Born Deaf

Chlidren born deaf have had their hearing restored in both ears as a result of gene therapy, a new study reports.

All five children showed hearing recovery in both ears, with dramatic improvements in speech perception and the ability to locate the position of a sound.

Two of the children also gained an ability to appreciate music, and were observed dancing to music, researchers added.

"The results from these studies are astounding,"said co-senior researcher Zheng-Yi Chen, an associate scientist in the Eaton-Peabody Laboratories at Mass Eye and Ear.

"We continue to see the hearing ability of treated children dramatically progress and the new study shows added benefits of the gene therapy when administrated to both ears, including the ability for sound source localization and improvements in speech recognition in noisy environments,"Chen added in a Mass Eye and Ear news release.

About 26 million people are born deaf, researchers said in background notes. Up to 60% of childhood deafness is caused by genetic factors.

The children in this study all had DFNB9, an inherited hearing condition caused by mutations in the OTOF gene, researchers said.

The condition prevents the production of functioning otoferlin protein, which is needed in the auditory and nerve mechanisms underlying hearing.

There currently are no drugs available to treat inherited deafness conditions like DFNB9, researchers said.

However, this gene therapy already has been proven to work, with a six-patient trial in 2022 showing recovery of hearing in one ear for five kids.

For this study, researchers wanted to see if the gene therapy could restore hearing in both ears at the same time.

"Restoring hearing in both ears of children who are born deaf can maximize the benefits of hearing recovery,"said lead researcher Dr. Yilai Shu, director of the Diagnosis and Treatment Center of Genetic Hearing Loss affiliated with the Eye & ENT Hospital of Fudan University in Shanghai. 

The children received functioning copies of the OTOF gene through injections of a virus into their inner ears, starting in June 2023. The hollowed-out virus carried copies of the healthy gene.

The kids were treated at the Eye & ENT Hospital of Fudan University and observed for either a 13-week or 26-week period.

Researchers were concerned a double-dose of the virus might cause a stronger immune response, increasing the risk of adverse effects. However, no serious toxicity or serious side effects were observed.

The new study was published June 5 in the journal Nature Medicine.

"Our study strongly supports treating children with DFNB9 in both ears, and our hope is this trial can expand and this approach can also be looked at for deafness caused by other genes or non-genetic causes,"Chen said. "Our ultimate goal is to help people regain hearing no matter how their hearing loss was caused."

More information

Johns Hopkins Medicine has more on hearing loss in children.

SOURCE: Mass Eye and Ear, news release, June 5, 2024