Prognostic impact of RUNX1 and ETV6 gene copy number on pediatric B-cell precursor acute lymphoblastic leukemia with or without hyperdiploidy.

The ETV6/RUNX1 fusion gene is a valuable prognostic marker that is frequently observed in B-cell precursor acute lymphoblastic leukemia (B-cell ALL). However, the clinical significance of copy number aberrations in these genes remains unclear. In this study, the effects of various aberrations inETV6 and RUNX1 gene copy number on disease prognosis were evaluated in 21 pediatric patients diagnosed with B-cell ALL with/without t(12;21). The prognostic significance of changes in gene copy number of ETV6 or RUNX1 in the presence or absence of hyperdiploidy, trisomy 21, and t(12;21) translocation were also evaluated. RUNX1 gene copy number amplifications were detected in 83 % of the patients who lacked t(12;21) and in all of the patients with hyperdiploidy. Trisomy 21 was detected in 78 % of the patients with hyperdiploidy. Changes in ETV6 gene copy number were detected in patients who lacked both the t(12;21) translocation and RUNX1 gene copy number amplifications. However, RUNX1 gene copy number amplification and ETV6 deletion were observed in all of the patients with t(12;21). RUNX1 gene copy number amplification was associated with hyperdiploidy, but not with t(12;21). Thus, the evaluation of distinct FISH and cytogenetic patterns in patients with B-cell ALL may strengthen the prognostic significance of changes in gene copy number.