Abstract

The patterns of chromosomal abnormalities in acute myeloid leukaemia (AML) revealed by study of peripheral blood specimens (group A) up to seven days old were comparable to the results from fresh bone marrow (group B). However, a decreasing proportion of cases providing enough metaphases for study, an increasing proportion of cases with chromosomal abnormalities, a decreasing ratio AN:AN + AA (see footnote Table 1) and a decreasing percentage of chromosomally normal cells in AN cases were found with ageing of specimens, which clearly demonstrates that cells with a normal karyotype were more likely to lose the capacity for dividing and die off than abnormal ones during ageing of specimens. Since the cells in older specimens were less active in division, a prolonged culture time was used. The different times for the cells from older specimens to re-enter active proliferation in culture conditions appeared to have some cytobiological significance. Three cases with t(8q-; 21q+) were present in group A but none in group B. Two cases of APL both showed a t(15q+; 17q-) and the breakpoints seemed to be at 15q24 and 17q22. One case showed trisomy 8 and double minute chromosomes. The remission rate in AN patients was lower than in AA or NN patients.