ABL1 and acute lymphoblastic leukemia: 1). The RT-qPCR results support the data obtained by FISH and sequencing revealed the presence of TEL/AML1 fusion transcript in all the analyzed subpopulations except Pre-Pro B cells (Suppl. Tab. 2). Moreover, TEL/AML1, BCR/ABL PFGs as well as MLL gains and deletions were detected in most of the analyzed subpopulations (Suppl. Tab. 1, 3 and 4). Patient 4 showed the highest degree of genetic instability of ALL associated genes in HSPC reaching 38.6% of aberrant cells in HSC/MPP, which is the most probably the leukemogenic subpopulation in this patient (Suppl. Tab. 1, 3 and 4).