miRNA dysregulation in cancer was first reported in 2002, when miR-15 and miR-16 were identified at 13q14.3, a frequently deleted region in chronic lymphocytic leukemia (CLL), leading to the overexpression of their target, i.e., BCL-2 (B cell lymphoma 2) [82]. This evidence concerns the gene BCL2 and B-cell chronic lymphocytic leukemia.