Zhou Yangyang (3 years old), who was completely deaf just a few months ago, can now call his parents “Mom” and “Dad” and name colors.
This boy is one of 5 children who were able to hear for the first time thanks to a revolutionary gene therapy he received as part of a clinical trial conducted by Chinese and American researchers.
This treatment provides new hope for these children who have been infected with a rare genetic mutation since birth.
Zhang Yi (Chu Yangyang’s mother) stated that she was moved to the point of tears when she realized, after 3 months of treatment, that her child could hear the sound of her knocking on the door.
She told Agence France-Presse – in an interview from Shanghai – “I hid in a closet and called him, and he answered.”
This study – published today, Wednesday, in the journal Nature Medicine – details the results of the first application of this gene therapy procedure to both ears. This procedure resulted in better language perception and a greater ability to find the source of sound than treatment with one ear provides.
Zeng Yi Chen, a researcher at Eaton Peabody Laboratories, explained to Agence France-Presse that this study, which he was responsible for, represented a “decisive turning point,” adding that companies were now conducting clinical studies, including two in Boston, to obtain permission to use the treatment.
He added, “If the results remain the same, and no complications are observed, I believe that the procedure could be approved within 3 to 5 years.”
Rare mutant
About 26 million people suffer from a hereditary form of deafness all over the world. This gene therapy focuses on a mutation that occurs in between 2 and 8% of cases.
These patients are unable to produce otoferlin, a protein needed by hair cells in the inner ear to convert sound vibrations into chemical signals that are sent to the brain.
The procedure involves injecting a modified virus into the inner ear that reflects the mutant that causes deafness.
For his part, Yilai Xu, a researcher at Yangyang Hospital in Shanghai, who participated in preparing the study, said that “all family members,” including Zhou Yangyang’s mother and grandmother, “cried when they realized that the child had become able to hear for the first time.”
His mother, a 26-year-old housewife, noticed that caring for her son had become easier since he started speaking, and the family hopes to transfer him from a specialized school to a traditional kindergarten.
New challenges
Lilai Xu previously managed a research team that in 2022 achieved the first gene therapy of this kind. He told Agence France-Presse that treating both ears presented new problems, because doubling the surgeries increases the risk of side effects.
But only mild or moderate side effects, such as fever, vomiting, or a slight increase in white blood cells, have been reported.
Significant progress was noted in the five children, aged between one and 11 years, and two of them were able to listen to music, although hearing this audio signal is more difficult, and they even danced, according to videos recorded for the study.
It was amazing that the 11-year-old child was able to understand language more and speak better, despite the prevailing belief that it was too late for the brain to acquire this ability as he had never heard voices before.
Cheng Yiqin saw this as “evidence that the brain has plasticity that may last longer than initially thought.”
The study will continue and patients will be monitored long-term.