Microarrays and gene expression profiling for the diagnosis in leukemia. From research studies to routine application

So far, the diagnosis in leukemia is based on cytomorphology and cytochemistry, multiparameter flow cytometry, combined with cytogenetics, fluorescence in situ hybridization, and polymerase chain reaction (PCR). This allows classification and definition of biologically defined and prognostically relevant subtypes in nearly all cases. It led also in same subgroups to targeted treatment approaches. Today, microarray technology enables us to quantify simultaneously the expression status of many ten thousands of genes in one single experiment. This novel tool seems able to renew the diagnosis and classification in leukemia and may even become essential for the molecular classification of leukemias in the near future. An ongoing international study (MILE study) is testing the accuracy, sensibility and specificity of gene expression profiling in leukemia diagnostics. First results and future directions will be given in the article.