Cytogenetic patterns in acute non-lymphocytic leukaemia

Abstract

Chromosome banding studies of the leukaemic cells of patients with acute non-lymphocytic leukaemia (A.N.L.L.) show that both numerical and structural changes occur in 50-60% of patients examined at diagnosis. Identification of chromosomes involved in both types of change indicate that there is a non-random involvement of specific chromosomes. In addition, cytogenetic subgroups can be identified which appear to have prognostic implications. This paper reviews the results of chromosome studies in A.N.L.L. performed in the cytogenetic research unit at St St Vincent’s Hospital, from 1975 to 1978. Using short-term marrow cultures, chromosome studies were carried out on 168 patients at diagnosis; 102 were found to have abnormal karyotypes and 48 showed no chromosome abnormality. No mitoses were obtained from 18 patients. To date trypsin G-banding studies have been satisfactorily performed on 47, of whom 37 had abnormalities. The most common abnormality was trisomy 8. A specific translocation between 8 and 21 was identified in 3 patients and a 9;22 translocation in 2 others. All patients with acute erythroleukaemia, and the majority with A.N.L.L. occurring after long-term therapy for other haematological disorders, had abnormal karyotypes with multiple abnormalities. The response of these patients to therapy was poor, whereas those with specific translocations all achieved remission. Ten of 12 patients considered to have a preleukaemic syndrome showed chromosome abnormalities which were most frequently monosomy 7 or partial deletion of the long arms of chromosome 5,(5q-). Similar findings have been reported in other series, but the frequency of occurrence appears to show geographical variation. Therefore as cytogenetic patterns seem to have diagnostic, prognostic and aetiological implications in A.N.L.L., chromosome studies should always be performed at diagnosis.