Restoring RBM20. This image shows cardiac tissue from mice carrying an R636Q mutation in the gene encoding RNA binding motif protein 20 (RBM20). In this image, precise in vivo adenine base editing (ABE) has restored the localization of RBM20 (green) to the nucleus (blue) and markedly reduced ribonucleoprotein granules outside the nucleus (cardiac troponin T is shown in red). Nishiyama et al. used ABE and prime editing to precisely correct mutations in RBM20, which are common causes of familial dilated cardiomyopathy, in pluripotent stem cells in vitro. In R636Q/R636Q mice, ABE resulted in improved RBM20 localization, cardiac function, and lifespan, suggesting that these precise editing approaches may be able to treat familial dilated cardiomyopathies.