Scientists at Harvard Medical School and Boston Children's Hospital have used a novel gene-editing approach to salvage the hearing of mice with genetic hearing loss and succeeded in doing so without any apparent off-target effects as a result of the treatment.
source https://www.lifetechnology.com/blogs/life-technology-news-blog/optimized-gene-editing-tool-prevents-hearing-loss-in-mice-with-hereditary-deafness-without-detectable-off-target-effects