TAL1 and acute lymphoblastic leukemia: The largest subgroup, representing about 30–35% of T-ALL, is characterized by the abnormal expression of TAL1 (1p32), a bHLH member, which results from either t(1;14) (p32;q11), and t(1;7) (p32;q35) translocations, small insertions, mutations or 1p32 deletion (36, 37).