Gene Therapy Gives New Hope for Deaf Teens

A study followed people with a specific genetic hearing loss called OTOF‑related deafness for two and a half years after they received a gene therapy. The treatment used a harmless virus to deliver a healthy copy of the missing gene into inner‑ear cells. Researchers checked many things over time, such as how well the virus stayed inside the body and how hearing improved. First, they measured antibodies that could block the therapy’s virus. The average level of these antibodies rose a little after treatment but stayed low enough that the therapy kept working for most patients. This shows the body did not mount a strong attack against the virus. Next, scientists measured hearing thresholds using three tests: brain‑stem response (ABR), steady‑state response (ASSR) and ordinary hearing tests. They recorded these at several points: before treatment, after 6 weeks, 13 weeks, 26 weeks, one year, and up to two and a half years. Most people who responded showed better hearing at all frequencies, especially between 0. 5 and 4 kHz. The improvement was seen in both ears for many patients.The study also compared two dose levels of the virus. The higher dose was given later, after the lower dose proved safe and effective. Results from both groups were similar, suggesting the smaller dose was enough for most patients. Age mattered too. Children under three years old showed the biggest gains, while adults over 18 had smaller improvements. This pattern fits with other research that younger ears respond better to gene therapy. Researchers looked at a different test called distortion‑product otoacoustic emission (DPOAE). The signal‑to‑noise ratio of this test at baseline predicted how much hearing would improve after 26 weeks. In other words, patients with clearer ear sounds before treatment tended to gain more hearing. Finally, the team examined how different genetic mutations affected outcomes. Patients with two non‑truncating mutations did slightly better than those with truncating ones, but overall all groups benefited. This suggests the therapy can help a broad range of genetic causes. In sum, this long‑term follow‑up shows that gene therapy for OTOF deafness is safe, can improve hearing for many people, and works best when started early. The findings give hope to families dealing with inherited hearing loss.