Breakthrough gene editing technology may prevent hearing loss in humans

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New Delhi: US researchers, with the help of gene editing technology CRISPR, have edited a gene variant that leads to deafness in mice, a breakthrough that could transform future treatment of genetic hearing loss in humans.

Hearing loss is the most common form of sensory loss in humans, and almost half of cases have an underlying genetic component.

The findings showed that a single treatment involving injection of the gene tool CRISPR-Cas9 cocktail prevented progressive hearing loss in young animals that would have otherwise gone deaf.

"We hope that the work will one day inform the development of a cure for certain forms of genetic deafness in people," said David Liu, researcher at Howard Hughes Medical Institute (HHMI) -- a US-based non-profit.

In the study, detailed in the journal Nature, the team focused on a mutation in a gene called Tmc1 -- a single spelling error in the genetic code, that causes the loss of the inner ear's hair cells over time.

Just one copy of a mutated Tmc1 gene causes progressive hearing loss leading to profound deafness, both in humans and in mice. 

The researchers used CRISPR-Cas9 technology that acts as molecular scissors, snipping the genome to disable a target gene, and injected the gene editing solution directly into the infant mice's hair cells -- the sound-sensing cells of the inner ear -- with the hearing loss mutation.

Once the mutated gene was disabled, the inner ear hair cells survived, and mice otherwise genetically destined to become deaf retained a portion of their hearing.

After eight weeks, the hair cells in treated ears resembled those in healthy animals, densely packed and tufted with hairlike bundles. The hair cells of untreated mice, in contrast, looked damaged and sparse.

If used in humans, the treatment could be best during childhood, because hair cell loss in the inner ear is progressive and irreversible, Liu added. 

(With Agency inputs)