Gene expression profiling as a diagnostic tool in acute myeloid leukemia.

The standard methods for establishing the diagnosis of acute leukemias are cytomorphology and cytochemistry in combination with multiparameter immunophenotyping. Cytogenetics, fluorescence in situ hybridization, and PCR-based assays add important information regarding biologically defined and prognostically relevant subgroups, and allow a comprehensive diagnosis of well-defined subentities. In the clinical setting, a better understanding of the clinical course of distinct, biologically defined disease subtypes is the basis for a selection of disease-specific therapeutic approaches. As knowledge of deregulated pathways in leukemia increases and accelerates the development of new therapeutics, a detailed and comprehensive diagnostic tool is required. Microarray technology, which quantifies gene expression intensities of thousands of genes in a single analysis, has the potential to become an essential tool for the molecular classification of leukemias. It may, therefore, be used as a routine method for diagnostic purposes in the near future. Furthermore, gene expression profiling may also lead to the detection of new biologically defined and clinically relevant subtypes in leukemia and guide therapeutic decision-making in the future.