A seven-year-old girl, born deaf, could have conversations with her mother just four months after a single shot. This injection into her inner ear gave her a missing gene. It was not a hearing aid or an implant.
Researchers at Karolinska Institutet and hospitals in China published these findings in Nature Medicine. Their trial involved ten patients with congenital deafness. This deafness was caused by changes in a gene called OTOF.
Every patient showed better hearing. Most noticed changes within one month. After six months, patients could hear sounds at 52 decibels. Before treatment, they could only hear sounds at 106 decibels. This is like the difference between a jackhammer and a normal conversation.
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Start Your News DetoxHow the OTOF Gene Works
The OTOF gene makes a protein called otoferlin. This protein acts like a switch in the inner ear's hair cells. When sound waves make these cells vibrate, otoferlin releases signals. These signals go to the brain, allowing us to hear.
Without otoferlin, the ear can still receive sound. However, the signal never reaches the brain. The hearing process stops before it truly begins.
The new therapy uses a harmless virus to deliver a working copy of the OTOF gene. This gene is injected directly into the cochlea, a part of the inner ear. The virus carries the correct gene into the hair cells. It does not change the surrounding tissue.
Who Benefits Most
Younger patients, between five and eight years old, showed the biggest improvements. Their brains seem better at adapting to new sound signals. However, even adults in the trial improved.
Dr. Maoli Duan from Karolinska Institutet noted that earlier studies in China showed good results in children. This new trial is the first to include teenagers and adults. He said that many participants had much better hearing, which greatly improved their lives.
The youngest patient in the trial was one year old. The oldest was 24.
Safety and Future Steps
No serious side effects were seen during the six to twelve months after treatment. The most common side effect was a temporary drop in white blood cells called neutrophils.
OTOF gene changes cause a small part of genetic hearing loss. Other gene changes, like GJB2 and TMC1, are more common worldwide. These are harder to treat. This is partly because of how they interact with surrounding tissues and the size of the proteins involved.
Dr. Duan believes OTOF is just the start. Researchers are now working on treatments for more common genes that cause deafness, like GJB2 and TMC1. Animal studies for these genes have shown promising results. Researchers are hopeful that people with different types of genetic deafness will eventually get treatment.
Otovia Therapeutics Inc. helped fund this research. The company also employs some of the researchers. Long-term follow-up is still happening to see how lasting the effects are. The current data shows that everyone in the trial heard better after treatment.
Deep Dive & References
AAV gene therapy for autosomal recessive deafness 9: a single-arm trial - Nature Medicine, 2024
