RUNX1 and precursor B-cell acute lymphoblastic leukemia: The most frequent B-ALL (∼22%) is characterized by the chromosomal translocation t(12;21)(p13;q22) that results in the fusion of two transcription factors, ETV6 and RUNX1, producing a functional fusion protein ETV6-RUNX1 previously known as TEL-AML1 [8, 9].