[The interest of standard and molecular cytogenetics for diagnosis of acute leukemia]

The standard and molecular cytogenetic techniques now belong to the panel of mandatory analyses performed at diagnosis of acute leukemia. Chromosomal abnormalities contribute to define different types of leukemias and present the major advantage to be effective and independent prognostic factors, essential for therapeutic choices. Cytogenetic techniques allowing to identify hyperdiploïdy >50 chromosomes, t(12;21)(p13;q22)/TEL-AML1(ETV6-CBFA2), t(9;22)(q34;q11)/BCR-ABL, 11q23/MLL, t(15;17)(q22;q12-21)/PML-RARalpha, t(8;21)(q22;q22)/AML1-ETO and inv(16)(p13q22)/ CBFbeta/MYH11 are developed. Among the techniques devoted to study genome, cytogenetics is a basic, simple and effective tool for giving a total picture of the genome through karyotype. Maintaining a systematic cytogenetic analysis is essential, not only because cytogenetics now belongs to routine practice but also because it still contributes to better defining morpho-immunologic sub-types of leukemia, to identify new cytogenetic entities and to understand hematopoiesis and leukemogenesis.