Iwasa et al. used woodchuck hepatitis virus post-transcriptional regulatory element (WPRE) to enhance Tmc1 transgene expression to result in poor hearing recovery [76] and found that the expression of Tmc1 in OHCs in animals treated with the WPRE-containing vector was higher than the group without WPRE through scRNA-seq analysis, with relatively better treatment effects, suggesting that optimizing the transgenic dose expressed in target cells is critical for gene therapy for hearing loss. Here, TMC1 is linked to hearing loss disorder.