Genetic classification of acute myeloid leukemia (AML)

In 50-60% of patients with acute myeloid leukemia (AML) acquired clonal chromosome aberrations can be observed after metaphase banding analyses. The cytogenetic results at diagnosis provide the most single important parameter for determining prognosis so far. Numerous recurrent karyotype abnormalities have been described in AML. These findings on the chromosomal level were followed and supplied by molecular studies that have identified genes involved in leukemogenesis. Even more, molecular markers such as MLL partial tandem duplications (MLL-PTD) or FLT3 length mutations (FLT3-LM) were found to characterize specific subtypes of AML and completed the genetic marker profile. The identification of specific chromosomal abnormalities or molecular markers and their correlation with cytomorphological features, immunophenotype as well as clinical outcome led to a new understanding of AML as a heterogeneous group of distinct biological entities. The importance of cytogenetic and molecular genetic findings in AML for classification and for the understanding of pathogenetic mechanisms is increasingly appreciated in clinical context and was translated also into the new WHO-classification of AML that uses cytogenetic abnormalities as a major criterion.