SRP125552 PRJNA398715 miR-mmPCR-seq Adenosine-to-inosine (A-to-I) RNA editing regulates miRNA biogenesis and function. To date, less than 160 miRNA editing sites have been identified. Here we present a quantitative atlas of miRNA A-to-I editing, through the profiling of 201 pri-miRNA samples and 4,694 mature miRNA samples in human, mouse, and Drosophila.