The reaction of children who heard the world for the first time thanks to gene therapy (5 photos + 2 videos)
A new treatment method has allowed six deaf children aged between one and 11 years to regain their hearing. The study involved patients who were treated in China and the USA. They were all born with a gene mutation that blocked the production of a protein necessary for hearing. 
Scientists introduced a version of a gene called otoferlin (OTOF) into the inner ear, and the cells began producing the missing protein.
After 26 weeks of treatment, the children's hearing level reached 70% of normal, and the effect began to appear already in the sixth week. 
Aissam Dam, 11, spoke for the first time this week after being treated at Children's Hospital of Philadelphia. The boy became the first person in the United States to undergo the revolutionary treatment.
Dam was born deaf due to an extremely rare abnormality in the OTOF gene, which was also observed in five children from China.
The defective gene prevents the production of otoferlin, a protein needed by the “hair cells” of the inner ear that convert sound vibrations into chemical signals transmitted to the brain.
In October, the boy underwent surgery to lift his eardrum and then inject him with a harmless virus that had been modified to carry copies of the otoferlin gene.
As a result, the hair cells began to produce the missing protein and function properly.
"Gene therapy for hearing loss is something that we as hearing loss physicians and scientists have been working on for over 20 years, and it's finally here," said Dr. John A. Jermiller of the Children's Hospital of Philadelphia.
"The results of this study are truly amazing. We saw week after week that the children's hearing ability improved significantly and their speech also recovered," said Zheng-Yi Chen, a professor at Harvard Medical School.
About 34 million children worldwide suffer from deafness or hearing loss, and in 60 percent of cases, genes are responsible.
The six-year-old girl Yi-Yi did not have the ability to speak, as she was deaf from birth. A month after the injection, the girl was able to hear and repeat what was said.
Queen Lixue covers her mouth to prevent Yi from reading her lips.
“Clouds, one after another, appear in the mountains,” says the woman. And the girl repeats after her without mistakes.
Yi and four other patients were treated at Fudan University Hospital in Shanghai, China. The results were published in The Lancet on January 24.
A total of six operations were performed in China, but one child's hearing did not improve due to immunity to the virus that was used to transfer the gene.
In the footage, a one-year-old child responds to her name for the first time, and another girl repeats “daddy,” “mom,” “grandmother,” “sister” and “I love you,” even though she could not speak before.
"Since cochlear implants were invented 60 years ago, there has been no effective treatment for deafness," says Chen. "This is a huge milestone that symbolizes a new era in the fight against hearing loss."
