Chromosome abnormalities in patients with chronic myelocytic leukemia.

Fifty patients with chronic myelocytic leukemia (CML) grouped into four stages on the basis of clinical and hematological results were analyzed with chromosomal banding techniques. Of the 50 patients, 48 hand the "standard" type of Ph1 translocation, t(9 ; 22) (q34 ; q11) and the remaining 2 had Ph1-negative diploid karyotype. The frequency of numerical chromosomal changes and/or structural chromosomal changes other than the Ph1 translocation varied with the stages; the frequency was 1 of 28 cases (3.6%) for patients in stage I (chronic phase), 5 of 11 (45.5%) in stage II (early stage of blastic phase), 11 of 13 (84.6%) in stage III (blastic phase) and 2 of 7 (28.6%) in stage IV (remission phase). Numerical changes in hyperdiploid leukemic cells correlated well with the appearance of extra #8 and extra Ph1 In 5 cases with hypodiploid leukemic cells, one of the #7 pair was absent in 4 cases and Y in 1 case. As structural changes, partial excess of chromosome 1, isochromosome 17q, isochromosome 1q, tdic (20p+ ; 21q-), del (7) (q11), t(2p+ ; 11p-), #12q+ and Xp+ were observed. Chromosomal analysis alone is not the best marker to diagnose the onset of blastic phase; however, it is a useful parameter when considered in combination with clinical and hematological results.