Derivative (7)t(7;8)(q34;q21). a new additional cytogenetic abnormality in acute promyelocytic leukemia.

Cytogenetic abnormalities in acute myelocytic leukemia (AML) have been identified as one of the most important prognostic factors. The t(15;17) is associated with high rates of complete remission and event-free survival. Secondary chromosomal changes are also present in approximately one third of patients with newly diagnosed acute promyelocytic leukemia (APL). Indeed, the gain of whole chromosome 8 may be involved in the course of APL under C-MYC gene dosage effect theory. Complete or partial loss of the long arm of chromosome 7 region has been recognized in preleukemic myelodysplasia or unfavorable AML. We report here two original APL cases in which a new additional chromosomal abnormality, der(7)t(7;8)(q34;q21), is associated with the t(15;17)(q22;q21). This recurrent abnormality results in a partial loss of 7q associated with a partial 8q trisomy. As the 7q and 8q breakpoints were similar in both cases, the involvement of these critical regions in the pathogenesis and outcome of APL disease has to be determined.