[Chromosomal aberrations in differential diagnosis and prognosis in childhood acute leukaemias]

The purpose of our study was to determine the frequency of specific, somatic chromosomal abnormalities in children with acute leukaemia and to evaluate the usefulness of cytogenetic study and DNA analysis as diagnostic and prognostic tools in these diseases. Among 63 children with acute lymphoblastic leukaemia (ALL) and 13 with de novo acute myeloblastic leukaemia (AML), hyperdiploidy was found in 25% and hypodiploidy in 6% of patients. Normal karyotype was found in 44% whereas pseudodiploidy in 25% of children with ALL. In the group of children with AML, pseudodiploidy was found in 2 cases and normal karyotype in 11. Translocations t(12;21), t(4;11), t(6;11) and t(9;11) failed to be detected by conventional cytogenetics. They were found by molecular methods. On the other hand, the t(1;14) and t(8;14) translocations were detected exclusively by karyotype analysis. The probability of event-free survival (EFS) in the group of children with ALL and genetic abnormalities of favourable prognosis was 96% whereas in the group of children with unfavourable prognosis it was 55%. Classical cytogenetic methods together with more sensitive molecular tests allow to detect diagnostically and prognostically relevant chromosomal aberrations in childhood acute leukaemias.