How to assess minimal residual disease in pediatric and adult acute myeloid leukemia?

Complete remissions that are reached after therapy of acute leukemia patients are classically defined as <5% blast cells in the bone marrow as determined by morphology. Unfortunately, a high percentage of patients in remission ultimately relapse, usually within the first years (1). In order to improve prognostic value of blast counts, another approach has been embarked upon, namely the detection of minimal residual disease (MRD).