SNPs’ functional effect on miRNAs’ activity. Gene localization of SNPs will determine the effect on miRNA activity. (A) SNPs located in the promoter region could modify the expression levels of the mature miRNA, altering the interaction with mRNA target that codes for transcriptional factors involved in the development and differentiation of lymphoid blasts. The interaction between miRNA–mRNA target could promote the subexpression of tumor-suppressor genes, leading to the development, proliferation, and progression of leukemic cells. (B) SNPs located on the gene structure would give rise to unstable miRNAs that increase their degradation rate or whose sequence change prevents the miRNA–mRNA target interaction, promoting the overexpression of oncogenes and eventually the progression of leukemic cells.