Novel gene therapy allows children to hear - 18th March 2024

Five children born deaf due to a genetic mutation can now hear thanks to a novel gene therapy treatment pioneered by biomedical researchers from Harvard University in the US and Fudan University in China. The study involved six children aged from one to seven, each with a mutation of the OTOF gene, which usually instructs cells to produce proteins that transmit auditory information to the brain.

Gene therapy utilises viruses as viral vectors – delivery agents carrying healthy genetic material to modify the DNA in target cells. Despite this being common practice, researchers encountered a stumbling block since one vector could not accommodate the entire OTOF gene.

This led to the innovation of splitting the gene's DNA into two parts, carried by two viral vectors. Having been injected into the inner ear to reach the target cells, the DNA halves were inserted into the cell, prompting the production of proteins.

The 26 week trial charted significant, progressive improvements in five of the six children, resulting in them being able to comprehend and respond to spoken stimuli. Speculation over why the treatment proved ineffective in one participant centres around a possible immune reaction to the viral vector. However, results in a one year old subject even saw the baby beginning to verbalise rudimentary words such as "mama".

Recent research into auditory treatment's been accelerated by the fact that hearing loss affects 1.6 billion people worldwide, although in the majority of cases this is owing to excessive exposure to environmental noise rather than a genetic condition.

The form of genetic deafness treated in this study, experienced by around 200,000 people, involves no physical problems with the ear. The relatively low patient numbers raise doubts over whether pharmaceutical companies will deem it worthwhile to develop this treatment at scale.

Co-authors Zheng-Yi Chen and Yilai Shu remain upbeat, anticipating US federal regulators to approve the treatment over the next three to five years. The delight of the children's parents has galvanised Shu, as he reports that , "They were very, very excited, and all of them cried when they first found that their child can hear."