Cytogenetic analysis of bone marrow from patients with primary myelodysplastic syndrome.

Of 34 patients with primary myelodysplastic syndrome (MDS), 26 (76.5%) were found to have chromosome defects using an improved bone marrow culture method and high-resolution G-banding technique induced by actinomycin D. The frequency of abnormalities varied among the subtypes: 1/2 in refractory anaemia with ringed sideroblasts; 18/24 in refractory anaemia; 5/6 in refractory anaemia with excess of blasts (RAEB); and 2/2 in refractory anaemia with excess of blasts in transformation. The most frequent abnormalities, either single, double or complex defects, were -5/5q-, -7, +8 and +21; 16q-/16p-, +19 and -X were also common. The percentage of aneuploid cells, in particular hypodiploid cells, was increased. The abnormalities were detected more frequently in complex aberrations associated with RAEB and RAEB in transformation. The presence of -5/5q- as a sole aberration was associated with longer mean survival time (greater than 18 months) but multiple (more than two) chromosomal abnormalities were associated with a poorer prognosis and a mean survival time of only 7.5 months. Chromosome follow-up studies indicated that patients with -7, +8, +21, -X and complex defects, increased hypodiploid cells and karyotpic evolution were likely to have a high risk of transformation to leukaemia or to a more severe subtype of MDS with a short overall mean survival time. These defects, mostly of the deleted type, are assumed to play a specific role in the pathogenesis of myelodysplasia. Repeated chromosomal analyses during the clinical course convey more accurate prognostic criteria for patients.