Two pairs of siblings born deaf are now responding to sound after a one-time gene therapy for a rare inherited form of hearing loss, according to their doctors and parents. In Wisconsin, 3-year-old Cleo and her younger sister Lennon were treated in July at Children’s Wisconsin, among the first children in the US to get the surgery1. In Cincinnati, a brother and sister from Uzbekistan, Abdu and Sumaya, were treated at Cincinnati Children’s as part of a clinical trial2.
The therapy is called Otarmeni (lunsotogene parvec-cwha) and was developed by the drugmaker Regeneron3. The US Food and Drug Administration (FDA) approved it in April 2026 as the first gene therapy for genetic hearing loss, according to the Alabama Department of Public Health4.
What the families are seeing
This summer at daycare in northeast Wisconsin, Cleo did something she had never done before: she ran to the window after hearing a dog bark, Wisconsin Public Radio (WPR) reported1. Since birth, she and her sister had not responded to sounds like clapping or humming1. Their mother, Emily Plumb, said results take months to show fully, but the family is seeing signs of improvement1.
“We are definitely seeing responses to sounds that she wouldn’t have responded to before.”
That is how Emily Plumb described it to WPR1. Dr. Karl Doerfer, hearing loss director at the Medical College of Wisconsin and Children’s Wisconsin and a co-surgeon on the procedure, told WPR that “the prognosis is excellent”1.
In Cincinnati, Abdu was treated in 2025 at age 3. He went from hearing almost no sounds to detecting sounds within four weeks, the hospital said, and he is now hearing in the normal range and has begun developing speech3. His results led to treatment for his 1-year-old sister, Sumaya, who the hospital said also has dramatically improved hearing3. Dr. John Greinwald, the ear specialist who treated them, told the Cincinnati TV station WLWT that within weeks both children could hear without implants or devices, and that their hearing shows signs of continued improvement2.
How the therapy works
Children with this condition have faulty versions of both copies of a gene called OTOF3. The gene makes a protein, otoferlin, that helps pass signals from the inner ear’s sensory “hair cells” to the hearing nerve3. A pediatric audiologist at Children’s Wisconsin, Brittney Gniedziejko, explained to WPR that the ear’s structures work, but the sound is not passed from the inner ear to the nerve and brain. She said one surgeon compares it to drafting an email and never hitting send1.
The treatment uses harmless carrier viruses (a “dual AAV1 vector”) to deliver a working copy of the gene directly into the cochlea, the snail-shaped hearing organ3. Surgeons reach it from behind the ear, much like cochlear implant surgery, and infuse the drug into the inner ear fluid while the child is under general anesthesia3. In Alabama’s case, the state described it as a same-day surgical procedure4.
The condition is rare: about 20 to 50 Americans are born with it each year, and roughly 200,000 people worldwide have it, WPR reported1. It accounts for an estimated 1% of deafness present at birth3. Untreated, these children cannot hear noises as loud as a running lawnmower a few feet away3.
The evidence so far
The main published evidence comes from a trial reported in The New England Journal of Medicine, co-authored by Greinwald3. By 24 weeks, 9 of the first 12 children could hear sounds of 70 decibels or quieter, a level that generally avoids the need for a cochlear implant3. Four reached normal or near-normal hearing, and four had mild to moderate hearing loss that let them hear normally with standard hearing aids3. One child did not respond at all, for reasons that remain unclear3.
The hospital also noted that hearing improved in participants as old as 16, which it said challenges an earlier assumption that gene therapy for deafness could only succeed in infancy3. Earlier reporting, from Medscape via the University of Cincinnati, said children treated with gene therapy did better than children with cochlear implants alone at detecting speech in noisy settings and at perceiving music5.
The two Cincinnati siblings were in the second group of trial participants, after the first 123. Their results, and those of other newer cases, have not yet been published. The hospital said more results were expected to be presented in October 2026 and included in a future journal paper3.
What it does not show yet
The numbers are small, and follow-up is short. Not every patient who got the therapy had better hearing, WPR noted, and because the treatment is new, no one knows how long it will last1. Greinwald, by contrast, told WLWT that the therapy “is predicted to last a lifetime”2. That is a prediction, not something measured yet.
Timing is a real concern for families. Dr. Daniel Choo, director of pediatric ear, nose and throat care at the University of Cincinnati College of Medicine and Cincinnati Children’s, said the best window for learning language runs from birth to age 35. Judging whether the gene therapy worked in a child can take up to 18 months, which complicates the choice between gene therapy and a cochlear implant5. Choo said in late 2025 that the implant was “still the best standard of care right now,” because doctors can predict its results, while for gene therapy “for some kids, it doesn’t work at all”5.
The Plumbs have backup plans, including a cochlear implant, if the surgery ultimately does not succeed, and Cleo continues to learn sign language1. Both girls have access to speech and language therapy1. Doerfer said that support after surgery is critical to how far these children develop1.
Who is behind it
Regeneron developed the therapy3. Some of the hospital’s materials also refer to it by its development code, DB-OTO6. The Cincinnati results described here come from the hospital’s own announcement, written under Greinwald’s name, and Greinwald co-authored the journal study3. The hospital called the result “a medical miracle” in its own words; Biohack reports the measured outcomes rather than that framing.
The therapy has been given at several centers. WPR reported it had only been performed in Milwaukee, Boston and California1, while Cincinnati Children’s says it treated the brother and sister as trial participants3. An Alabama child covered by the state’s children’s health insurance program was treated at Boston Children’s Hospital, one of the original trial sites4.
How it fits the field and what to watch
The first clinical trial results for this approach were published in 2022, and since then five research groups in the US, China and France have worked on drugs targeting the same gene, according to the University of Cincinnati5. Choo is the site lead for an upcoming Eli Lilly trial at Cincinnati Children’s5. At least 150 genes are linked to hearing loss, and Choo said this gene stands out for its safety profile because it is only switched on inside the cochlea5.
Genetic causes account for up to half of childhood deafness, but each gene would need its own customized treatment, the hospital said3. Doerfer called the therapy “a proof of concept”1.
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