(Washington) Calling “mom” and “dad”, naming colors: Zhu Yangyang speaks today like a three-year-old child, a feat, whereas he was completely deaf just a few months ago.
Zhu Yangyang is one of five children who were able to hear for the first time thanks to a revolutionary gene therapy, carried out as part of a clinical trial led by Chinese and American researchers.
New hope for these children born with a rare genetic mutation.
Zhu Yangyang’s mother, Chang Yiyi, said she was moved to tears when she realized, three months after treatment, that her child could hear her knocking at the door.
“I hid in a closet, called him and he answered! “, she explained to AFP during an interview from Shanghai.
This study, published Wednesday in the prestigious journal Nature Medicine, describes the results of the first time such a gene therapy procedure has been applied to both ears. Compared to treatment on one, this procedure improved language perception and the ability to find the source of a sound.
“This is a turning point,” Zheng-Yi Chen, a researcher at Eaton-Peabody Laboratories and head of the study, told AFP, adding that companies are now conducting clinical studies, including two in Boston, to go towards regulatory authorization of the treatment.
“If the results hold up, without any complications, I think in three to five years the procedure could be approved,” he added.
Around 26 million people have a genetic form of deafness worldwide. This gene therapy focuses on a mutation which affects between 2 to 8% of these 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 sent to the brain.
The procedure involves injecting a modified virus into the inner ear to reverse the faulty mutation.
When they realized Zhu Yangyang could hear for the first time, “the whole family cried,” including his mother and grandmother, said Yilai Shu, one of the study’s authors and a researcher at Zhu Yangyang Hospital. Fudan University in Shanghai.
His mother, a 26-year-old housewife, also added that caring for her son has been easier since he started talking and the family hopes to transfer him from a special school to a traditional preschool.
Yilai Shu had already led a research team behind the first gene therapy of this type in 2022, paving the way for a treatment now administered to several children around the world, such as in the United States or in Britain.
Treating both ears posed new problems, he told AFP, because doubling up on surgical procedures increased the risk of side effects.
But only mild or moderate side effects, such as fever, vomiting or a small increase in white blood cells, have been observed.
All five children, aged 1 to 11, have made great progress. Two of them were able to enjoy music – an acoustic signal that is harder to perceive – and even danced, according to videos recorded for the study.
Surprisingly, even the 11-year-old child managed to better understand language and speak, although it was thought to be too late for the brain to acquire this ability without ever having perceived sounds previously.
“This shows that the brain has plasticity that may last longer than we originally thought,” Zheng-Yi Chen said. The study is ongoing and patients will be followed up long-term.
In the meantime, the two researchers announced that they had launched clinical trials on animals to develop treatments against other causes of genetic deafness, including that linked to the gene causing the most common deafness at birth.