Thanks to gene therapy, an 11-year-old boy can hear for the first time

Aissam Dam, an 11-year-old boy, grew up in a world of deep silence. He was born deaf and had never heard anything. While living in a poor community in Morocco, he expressed himself using a sign language he invented and had no education.

Last year, after he moved to Spain, his family took him to a hearing specialist, who made a surprising suggestion: Aissam could be eligible for a gene therapy clinical trial.

On October 4, Aissam was treated at the Children's Hospital of Philadelphia, becoming the first person to receive gene therapy for congenital deafness in the United States. The goal was to get him to hear, but the researchers had no idea if the treatment would work and, if so, how much he would hear.

The treatment was a success and introduced a child who had known nothing about sound to a new world.

“There is no sound I don't like,” Aissam said during an interview last week with the help of interpreters. “They are all good.”

While hundreds of millions of people in the world live with hearing loss defined as disabling, Aissam is among those whose deafness is congenital. It is an extremely rare form, caused by a mutation in a single gene, otoferlin. Otoferlin deafness affects approximately 200,000 people worldwide.

The goal of the gene therapy is to replace the mutated otoferlin gene in patients' ears with a functional gene.

Although it will be years before doctors enroll many more patients – and younger patients – to further test the therapy, researchers say success for patients like Aissam could lead to gene therapies that target other forms of congenital deafness.

It's a “groundbreaking” study, says Dr. Dylan K. Chan, pediatric otolaryngologist at the University of California, San Francisco, and director of the Children's Communication Center; he was not involved in the process.

The project in which Aissam participated is backed by Eli Lilly and a small biotechnology company it owns, Akouos. Researchers hope to eventually expand the study to six centers in the United States.