IKZF1 and acute lymphoblastic leukemia: Fragile genomic sites with open chromatin configuration, high level of transcription and early replication origin were described in mouse B cells in loci encoding important TFs (e.g. BACH2, IKZF1, FOXP1), while mutations and chromosomal rearrangements are often found in genes encoding B-cell TFs (e.g. PAX5, IKZF1, EBF1) in patients with acute lymphoblastic leukemia (54, 55).