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We have identified a novel 7.7 Mb del(8)(q23.2q24.11) in a patient progressing to acute myeloid leukemia (AML) following a 12-year stable phase of chronic myelomonocytic leukemia (CMML). A surprisingly high JAK2+ allelic burden of 92% at the time of AML led us to delineate the molecular aberrations relevant for leukemogenesis. While a frameshift mutation in the TET2 gene was stably present throughout the course of disease the JAK2 mutation was acquired after initial diagnosis of CMML. At progression aCGH revealed del(8q)(q23.2q24.11) encompassing various cancer relevant genes of which RAD21 and CSMD3 are of particular interest.

Although childhood T-cell acute lymphoblastic leukemia (T-ALL) is a high-risk disease the outcome can vary considerably. The varying outcomes suggest that unrecognized factors may contribute to disease progression. We report on a 2-year-old T-ALL patient presenting with a very short history of constipation and extreme hyperleukocytosis (WBC 882×10(9)/L). In her leukemic cells we detected the very rare translocation t(7;19)(q35;p13) and LYL1 overexpression. Additionally, we detected submicroscopic deletions at 4q25, 7q33 and 10q23 by oligo-aCGH analysis. We suggest that LYL1 overexpression contributed to the leukemic state and propose that the observed microdeletions may have influenced to the rapid disease progression.

Chronic myeloid neoplasms have susceptibility to transform into acute myeloid leukemia due to attainment of additional molecular lesions. We here describe the kinetics of a del(7q) driven leukemogenesis in a patient with multiple TET2 mutations and JAK2 V617F mutated chronic myeloproliferative neoplasm. The del(7q) emerged in the accelerated phase of disease, which was preceded by a lag phase of almost three years with normalized peripheral blood cell counts. Our results reveal that the del(7q), independently of other lesions, acts as a leukemic driver in this patient and that the stable long-lasting normalization of peripheral blood cell values concealed pending transformation.