Molecular evaluation of acute myeloid leukemias

Traditionally, acute myeloid leukemia (AML) has been diagnosed and classified based on the morphologic and cytochemical criteria of the French- American-British (FAB) classification system. However, more recent studies have demonstrated that the cytogenetic and molecular genetic abnormalities consistently associated with distinct forms of AML confer the most important prognostic information. Each broad category of de novo AML that arises in infants and children, young adults, and the elderly, or, AML arising secondary to antecedent myelodysplasia (MDS) or prior exposure to chemotherapy, radiotherapy, or environmental agents is characterized by distinct cytogenetic and molecular genetic abnormalities. Over the past 15 years, a number of these recurrent cytogenetic abnormalities have been cloned and characterized, yielding valuable insights into the mechanisms of leukemogenesis and providing powerful molecular tools for precise diagnosis and monitoring of minimal residual disease. As cytogenetic and molecular genetic characterization of AML cells is now considered crucial for both diagnostic and therapeutic decision-making, it is essential to have a working knowledge of the molecular basis of AML. This chapter reviews the molecular genetic features of different forms of AML and the new automated molecular technologies for residual disease assessment; the emerging molecular paradigms in this disease that are being exploited for therapeutic decision- making are presented.