Therefore, we set out to identify novel epigenetic regulators and kinases specifically essential to KMT2A-r ALL cells by applying in vitro clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein 9 (Cas9) knockout screens using synthetically designed single guide RNA (sgRNA) libraries [20,21] directed against the entire human epigenome and kinome [22,23]. This evidence concerns the gene KMT2A and acute lymphoblastic leukemia.