Two Children with Acute Lymphoblastic Leukemia and “Jumping” Translocations: Both Involve 1q23 as the Donor Breakpoint

“Jumping” translocations (JT) are relatively rare and are associated with poor prognosis. We report two male patients with childhood acute lymphoblastic leukemia (ALL) and abnormal cell lines detected on bone marrow cytogenetics. Diagnostic marrow cytogenetics were not available for either patient. In patient 1, approximately 11 years after diagnosis, cytogenetics revealed a single translocation, t(1;2)(q23;q32), which was followed by translocations t(1;22)(q23;p11) and t(1;1)(q23;q21.3). In patient 2, two translocations were present together, t(1;6)(q23;p21.3) and t(1;11)(q23;q21), 12 years after diagnosis. The unbalanced JTs in both patients resulted in partial trisomy for (1)(q23→qter). Both died within 1–2 years after the appearance of the JT. Our patients provide additional support for chromosome 1q preferential involvement in JTs, and that their appearance is associated with a poor prognosis.