During the first half of the 2020s, advances are made in developing a gene therapy, with some of the first clinical trials in humans. This follows earlier experiments on mice, in which a mutation of the TMC1 gene was repaired. Scientists treated the animals by injecting an engineered virus called adeno-associated virus 1, or AAV1, combined with a promoter – switching on the gene in sensory hair cells within the cochlea.*Following successful human trials and approval from regulators, it becomes possible for patients affected by the TMC1 mutation to have their genomes sequenced and their hearing restored by gene therapy. However, while TMC1 was known to account for up to 8% of genetic deafness cases, more than 70 other genes were also implicated. It would therefore be a number of decades before the condition was fully understood and curable for all patients. Nevertheless, gene therapy sees major growth in research and development during the 2020s. Other treatment options besides gene therapy are also making breakthroughs at this time including stem cells and various new biotech implants.