The article describes the development of a novel RNA-editing platform called RNA Editing for Programmable A to I Replacement (REPAIR) using the CRISPR-associated RNA-guided ribonuclease Cas13. The authors profiled various Cas13 orthologs and identified PspCas13b as the most efficient and specific for mammalian cell applications. They engineered catalytically inactive PspCas13b (dCas13b) to recruit the adenosine deaminase domain of ADAR2 (ADAR2D) to create dCas13b-ADAR2D, which can mediate precise adenosine-to-inosine (A-to-I) editing. REPAIR was shown to be highly specific and efficient in correcting disease-relevant mutations in mammalian cells. The authors further optimized the system by engineering a high-specificity variant, REPAIRv2, which significantly reduced off-target edits while maintaining high on-target efficacy. REPAIR offers advantages over other nucleic acid-editing tools, including the ability to target any adenosine in the transcriptome, lack of motif preferences, and transient editing that can be useful for treating diseases caused by temporary changes in cell state. The system has potential applications in treating genetic diseases, mimicking protective alleles, and modifying genetic function.The article describes the development of a novel RNA-editing platform called RNA Editing for Programmable A to I Replacement (REPAIR) using the CRISPR-associated RNA-guided ribonuclease Cas13. The authors profiled various Cas13 orthologs and identified PspCas13b as the most efficient and specific for mammalian cell applications. They engineered catalytically inactive PspCas13b (dCas13b) to recruit the adenosine deaminase domain of ADAR2 (ADAR2D) to create dCas13b-ADAR2D, which can mediate precise adenosine-to-inosine (A-to-I) editing. REPAIR was shown to be highly specific and efficient in correcting disease-relevant mutations in mammalian cells. The authors further optimized the system by engineering a high-specificity variant, REPAIRv2, which significantly reduced off-target edits while maintaining high on-target efficacy. REPAIR offers advantages over other nucleic acid-editing tools, including the ability to target any adenosine in the transcriptome, lack of motif preferences, and transient editing that can be useful for treating diseases caused by temporary changes in cell state. The system has potential applications in treating genetic diseases, mimicking protective alleles, and modifying genetic function.