Cytogenetics of secondary myelodysplasia (sMDS) and acute nonlymphocytic leukemia (sANLL)

Abstract

76 cases of secondary myelodysplasia (sMDS) and acute non-lymphocytic leukemia (sANLL) were cytogenetically analyzed. Among the 36 sMDS patients, 13 (36%) had only normal karyotypes whereas 23 (64%) displayed clonal chromosomal abnormalities. The most common aberrations were -7, 5q-, -5, and +8. In 10 patients (43% of the cytogenetically aberrant cases), clones with only one anomaly, mostly 5q- or -7, were found. Of the 40 sANLL patients, normal karyotypes were detected in 10 (25%). Among the 30 (75%) abnormal cases, the most frequent aberrations were -7, -5, +8, 7q-, -17, and +21. 12 patients (40%) had clones with single abnormalities, most often -7. In 4 sANLL patients cytogenetically unrelated clones were detected. A survey of all previously published secondary hematologic neoplasias reveals that the most frequent abnormalities in sMDS are -7 (41%), 5q- (28%), and -5 (11%), followed by der(21q), +8, 7q-, der(12p), t(1;7), -12, -17, der(17p), der(3p), der(6p), and -18. Clones with single aberrations have been found in 45% of the cases and cytogenetically unrelated clones have been described in 6%. The most common abnormalities in sANLL are -7 (38%), 5q- (17%), -5 (15%), +8 (13%), and -17 (11%), followed by der(3q), der(11q), der(12p), -21, 7q-, -18, der(3p), der(17p), +21, der(21q), der(6p), and -16. 38% of the sANLL patients have had clones with only one aberration and 3% have had unrelated clones. The frequencies of these nonrandom abnormalities in sMDS and sANLL are thus remarkably similar - the only exception appears to be 5q-, which is more common in sMDS. Also the mean number of abnormalities per case is similar - 5.3 in sMDS and 5.6 in sANLL. When the incidences of characteristic cytogenetic abnormalities were correlated with the type of previous therapy, -7 was found to be more frequent in sMDS and sANLL patients who had been exposed to chemotherapy whereas 5q- was associated with previous exposure to ionizing radiation in sMDS patients.