Mechanisms of dysregulated miRNA expression in AML. miRNA dysregulation can contribute to the development of AML. Thus far, numerous mechanisms by which miRNAs become dysregulated in AML have been identified, including (1) deletions leading to decreased miRNA expression, (2) improper expression because of close proximity to an oncogenic genomic region created as a result of either a translocation event or overexpression of a neighboring protein-coding gene, (3) copy number amplifications leading to increased miRNA expression, (4) epigenetic alterations affecting miRNA expression, (5) miRNA promoter regions being aberrantly targeted by dysregulated transcription factors or oncoproteins, and (6) dysregulated miRNA processing leading to altered levels of mature miRNAs.