KMT2A and cancer: Importantly, the sustained transcription of TERRA in MLL-r ALL does not appear to adversely affect genome stability, as indicated by lower rates of somatic alterations including copy number abnormalities such as deletions and amplifications, single-nucleotide mutations, or structural variations found in pediatric MLL-r ALL versus non-MLL-r ALL or other pediatric and adult cancers [60,61,62].