ABL1 gene deletion without BCR/ABL1 rearrangement in a young adolescent with precursor B-cell acute lymphoblastic leukemia: clinical study and literature review.

Entire ABL1 gene deletion without BCR/ABL1 rearrangement is a rare phenomenon, with only four cases previously reported. Here we describe a fifth case of ABL1 deletion without BCR/ABL1 rearrangement in an adolescent patient with precursor B-cell lymphoblastic leukemia (B-ALL) and review the relevant literature. It is not clear how ABL1 deletion affects leukemogenesis; however, it is plausible that ABL1 deletion without BCR/ABL1 rearrangement is a rare but recurrent genetic abnormality in precursor B-ALL patients. Further studies are needed to evaluate the extent of the submicroscopic defects in chromosome 9 including ABL1 gene deletion, as well as treatment response and prognosis in long-term follow-up of such patients.