Several recurrent balanced translocations and inversions, and their variants, are recognized in the WHO category acute myeloid leukemia (AML) with recurrent genetic abnormalities. Furthermore, several cytogenetic abnormalities are considered sufficient to establish the WHO diagnosis of AML with myelodysplasia-related features if 20% or more blood or marrow blasts are present.
t(8;21)(q21;q22) is the most common translocation in de novo AML occurring in up to 20% of adult and 40% of pediatric cases. The translocation fuses RUNX1 with RUNX1T1 to produce a RUNX1/RUNX1T1 fusion gene located on the derivative chromosome 8. For these patients, the prognosis after intensive chemotherapy is better than for the majority of AML patients. Small hidden interstitial insertions resulting in a RUNX1/RUNX1T1 rearrangement have been found, necessitating the use of a breakpoint spanning rather than a breakpoint flanking FISH probe.
Clinical Applications
- Acute Myelogenous Leukemia (AML)