A virus-based gene therapy – developed using animals – has allowed an 11-year-old boy, who has been deaf since birth, to hear for the first time.

Aissam Dam (pictured, centre) was born with an extremely rare genetic mutation that prevents the production of the protein otoferlin – the protein is needed so that the inner ear’s hair cells can convert sound vibrations into signals that can be processed by the brain.

Last October, he underwent surgery in the US at the Children’s Hospital of Philadelphia (CHOP), where a working copy of the otoferlin gene was injected into his ear – carried to the target by a harmless virus.

Aissam now only has moderate-to-mild hearing loss, as his ear’s hair cells are able to produce functioning otoferlin.

Several earlier studies, in mice and in monkeys, tested and confirmed that the virus-based gene therapy could work to prevent and reverse deafness.

Other trials of this treatment on children with congenital deafness are underway in the US, Europe and China.

Surgeon John Germiller, at CHOP, told Eagle News: “Gene therapy for hearing loss is something that we physicians and scientists in the world of hearing loss have been working toward for over 20 years, and it is finally here.”