miRNAs down-regulated in AML samples with respect to CD34⁺ cells and mature and hematopoietic precursors. (A,B) We selected the most differentiated miRNAs according to SAM score and fold change and measured them in a random group of 6 AML patients and 4 CD34 samples obtained from healthy donors by quantitative RT-PCR. Results are presented as fold change of the miRNA expression in AML samples with respect to the CD34⁺ expression from one healthy donor after normalization with let-7i and 2^Δ Ct conversion¹⁸  (thin bars represent standard deviations). The difference in miRNA expression between the 4 CD34s and all the 6 AML patients was statistically significant by the t test: miR-106a (P = .001), miR125a (P = .001), miR-126 (P = .001), miR-93(P = .001), miR-130a (P = .006), miR-146 (P = .001), except for miR-135 (P = .38). (C) Average miRNA expression (from 4 different healthy donors) of peripheral blood mature granulocytes and monocytes and bone marrow committed (erythrocytic and megakaryocytic) precursors and 6 AML patients compared with that of CD34⁺ cells after normalization and 2^Δ Ct conversion. The results are presented as fold change, with respect to the CD34⁺ cells, average miRNA expression. The down-regulation of miRNA expression in mature peripheral blood cells and committed precursors with respect to CD34 cells was statistically significant by t test (P < .05).