Why classical cytogenetics still matters in acute myeloid leukemia

Cytogenetic analyses were already performed on acute myeloid leukemia (AML) cases in the 1960s. At that time, however, these investigations were hampered by the lack of chromosome banding techniques, restricting the analyses to merely counting the chromosomes and identifying large structural chromosome changes. This dramatically changed when chromosome banding methods were introduced in the early 1970s [1]. Within just a few years, a large number of chromosomal aberrations were detected in AML, such as t(8;21)(q22;q22) [the first AML-specific translocation identified], inv(3) (q21q26), monosomy 5/del(5q), t(6;9)(p22;q34), monosomy 7/ del(7q), trisomy 8, t(15;17)(q24;q21), and complex karyotypes (CK), to name but a few. In parallel with the increasing number of AML-associated abnormalities reported in the following decade, it became apparent that many of them were associated with certain, sometimes characteristic, morphologic, immunophenotypic, and clinical features [2,3]. Today, identification of several specific chromosomal changes is essential for proper risk stratification, and, hence, for treatment decision. For example, some aberrations in AML are associated with a favorable outcome, such as t(8;21) and inv(16), and others with a dismal prognosis, such as inv(3), CK, and monosomal karyotype (MK) [2,4].