MLL-Duplications are Rare and Associated with Poor Prognosis in Acute Myeloid Leukemia

Partial tandem duplications (PTD) within the MLL-gene have been described in a limited number of patients with acute myeloid leukemia (AML). In this study a systematic screening of 387 unselected AML was performed to evaluate the real frequency and prognostic relevance of this molecular marker. The frequency of PTD in the analyzed 387 unselected patients at the RNA and DNA level was of 3.4%. Most but not all patients were karyotypically normal. It was never found in patients with t(15;17), t(8;21), inv(16), other AML specific reciprocal translocations, or complex karyotypes. All PTD positive cases revealed a very bad outcome. Thus PTD may be an early event in leukemia that defines a specific AML subgroup.