Constitutive 53BP1/?H2AX foci are increased in cells of ALL patients dependent on BCR-ABL and TEL-AML1 preleukemic gene fusions..     ///    "These translocations result in so called preleukemic gene fusions (PGFs), such as BCR-ABL and TEL-AML1, which generate hybrid proteins with altered properties. "    ///    There was also significant increased level of constitutive ?H2AX/53BP1 foci in cells from ALL patients harboring BCR-ABL or TEL-AML1 compared to patients without PGFs.     ///    BCR-ABL and TEL-AML1 were shown to be associated with increased constitutive DSBs in various model systems.     ///    We analyzed cells from peripheral blood and CD34-/CD34+ cells from bone marrow of pediatric acute lymphoblastic leukemia (ALL) patients harboring BCR-ABL or TEL-AML1.     ///    Our data on increased DSB levels in the BCR-ABL/TEL-AML1 patient's cells support a?model where BCR-ABL/TEL-AML1 induces DNA instability through facilitating mutagenesis and appearance of additional genetic alterations driving leukemogenesis.. 