Congenital deafness: Four children (who had never heard before) gain hearing thanks to gene therapy

Four children born deaf regained near-normal hearing. This was announced by researchers from Fudan University in Shanghai at a press conference held in Brussels at the end of last October. For the first time, sensation has been restored to humans thanks to genetic modification. “This is a huge achievement and the first of its kind in the world. “It gives us hope that one day we will be able to treat other genetic causes of deafness,” commented Nathalie Lundon, who runs the Pediatric Auditory Phonology Unit at the Necker-Enfants Pathology Hospital in Paris. According to what was reported by “Le Figaro”, the children suffered from an extremely rare genetic mutation that led to a deficiency of otoferlin, a protein necessary for communication between sensory hair cells and the auditory nerve in the inner ear. Adding a rescue gene to these cells, via a harmless viral vector, restored the children’s hearing after just a few weeks.

The virus

Injecting a viral vector into the inner ear, a delicate procedure, has the advantage of confining the product to the small enclosed space of the cochlea and concentrating its effect. This is an important result, achieved 19 years after the mutation and the Ottoferlin gene were identified by Christine Petit and her team at the Institut Pasteur. The procedure was tested in 2018 on mice, and has now worked on four children who were born deaf. Chinese researchers from Refreshgene Therapeutics in Shanghai benefited from the experience of audiologist Cheng Yi Chen, a researcher at Harvard Comprehensive Eye and Ear Hospital in the United States.

Other tests

This result gives hope for a successful outcome for three other clinical studies using the same genetic technology. The first, conducted by US biotech company Regeneron Pharmaceuticals, has just given a first positive result in a newborn and will involve 22 children in the USA, UK and Spain. The second, supported by the US pharmaceutical company Eli Lilly, will include 14 children in the United States and Taiwan. The third trial will be launched in a few weeks by the French biotechnology company Sensorion, in collaboration with teams of doctors from the Necker-Enfants Malades Hospital and researchers from the Institut Pasteur at the Testing Institute in Paris. Funded by the Anr Audinnove program of the French Ministry of Higher Education, Research and Innovation, it is now managed by Sensorion, which will also produce the viral vector carrying the repair gene. “Now we are just waiting for the approval of the medical and ethical committees to start clinical trials in Europe. “In particular, we had to carry out safety tests on the process and the vector in mice and monkeys,” Nathalie Lundon, who has been coordinating the project since 2020, told Le Figaro.

Congenital deafness, the gene therapy revolution

Currently, profound deafness of genetic origin can be treated with a cochlear implant: about twenty electrodes are inserted into the cochlea (part of the inner ear) in contact with the auditory nerve, to be stimulated via an external receiver. This hearing aid was a revolution, but its cost is high and its results vary from person to person. But in fact, there is a cure for deafness. “Instead, by injecting a gene that corrects thousands of hearing cells simultaneously, we can restore normal and perhaps permanent hearing, because these cells do not regenerate throughout life,” Natalie Lundon tells Le Figaro. However, we also need to work at the screening level: “It is now important to disseminate the measurement of auditory evoked potentials in maternity wards (headphones transmit sounds of precise frequency and intensity, and electrodes placed on the scalp record electrical reactions) Brain, ed.). This technology allows us to identify all types of deafness at birth,” concludes Lundon.

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