TMC1 mutations account for 4–8% of all cases of heritable hearing loss in the world.7,47,48 In this study, we used the CRISPR/CasRx system to downregulate the Tmc1Bth mRNA transcript in the Bth mouse model of human genetic deafness with less knockdown of Tmc1+ transcript (there is only a single nucleobase difference between the two transcripts) both in vitro and in vivo. This evidence concerns the gene TMC1 and hearing loss disorder.