Cytogenetic studies in preleukaemia using the G-banding staining technique.

15 patients with preleukaemia were cytogenetically studied during the preleukaemic state by using the G-banding staining technique. It was found that 9 patients had a completely normal karyotype, while the other 6 showed various chromosomal abnormalities, numerical (trisomies in 5 cases) and structural (deletion in 1 case and a marker chromosome in 1 case). The abnormalities concerned group C in all 6 cases, while group A was involved in 3 cases. G-banding technique revealed that trisomy C affected the chromosomes nos 8 (2 cases) and 9 (3 cases); also a deleted chromosome 11 (11q-) was identified in 1 case and a marker chromosome in 1, the origin of which was established as a translocation between chromosomes 3 and 6. The abnormalities of group A concerned chromosome no 3. The abnormalities found in our cases, using the G-banding technique, were similar to those described in acute leukaemia.