Cytogenetic studies in de novo acute nonlymphocytic leukemia

There is currently considerable interest in the cytogenetic analysis of leukemia. The improvement of banding techniques has made it possible to rather precisely identify deletion, translocation, inversions, and other structural chromosome abnormalities. Specific recurring chromosome abnormalities associated with distinctive morphologic features are thus increasingly recognized in acute nonlymphocytic leukemia. For example, uneven geographic distribution of nonrandom specific chromosome aberrations has been reported. We herein report the results of chromosome studies on 30 Chinese patients with de novo acute nonlymphocytic leukemia.

Cytogenetic studies were performed at Veterans General Hospital-Taipei, from 1988 to 1993, on unselected samples of 30 patients with de novo acute nonlymphocytic leukemia. Chromosome analysis was performed by short-term culture techniques on bone marrow material obtained from patients at diagnosis. Metaphase chromosomes were banded by the conventional trypsin-Giemsa banding technique and then karyotyped according to the International System for Human Cytogenetic Nomenclature (ISCN). Classification of leukemia was based on the criteria of the French-American-British cooperative group.

Of the 30 patients with adequate specimens, 17 (56%) demonstrated clonal chromosome abnormalities. Six patients were found to have structural rearrangements and seven patients have a numerical change as the sole abnormality. Four patients showed both structural and numerical anomalies. t(8;21) was found in 1 of the 8 M2 type ANLL patients and two of them had monosomy 21. Four of the 6 patients with acute promyelocytic leukemia (APL; M3 subtype) showed t(15;17). Two patients with M4 type leukemia and abnormal bone marrow eosinophils showed inv(16)(p13q22). One patient with M4 type leukemia demonstrated the loss of chromosome #7 and none showed the loss or deletion of chromosome #5.

This study revealed a consistent finding of t(15;17) in APL; however, a low incidence of t(8;21), -5/5q- and -7/7q- in our patients demonstrated the possible difference in the incidence of chromosomal abnormalities in ANLL between the oriental peoples and the whites.