A Novel and Cytogenetically Cryptic t(7;21)(q36.1;q22) Disrupting RUNX1 in Acute Myeloid Leukemia.

Translocations involving the RUNX1 transcription factor gene are frequently identified in leukemia patients, but the partner genes have been characterized in only about half of these cases. We report here a novel RUNX1 partner gene, KMT2C (MLL3), in a patient with de novo acute myeloid leukemia, having a novel and cytogenetically cryptic t(7;21)(q36.1;q22) leading to disruption of RUNX1 and KMT2C. This is the third cryptic RUNX1 rearrangement in myeloid and the fourth in hematologic malignancies.