[Cytogenetic studies on 334 myelodysplastic syndrome (MDS), aplastic anemia (AA) and other hematological diseases].

In order to distinguish various types of MDS, such as RA/AA, RA/ITP or RA/HA, from AA, ITP or HA, bone marrow (BM) cells were studied by using cytogenetic techniques including R-banding karyotypic analysis and sister chromatid differentiation (SCD) assay in 334 cases of hematological diseases (160 MDS, 54 RA/AA, RA/ITP or RA/HA; 60 AA, 3 other known anemias, 38 PNH and 19 ITP). The results showed: (1) karyotypes and SCD values were both normal in more than 90% of AA, PNH, ITP and other known anemias, but they were both abnormal in about 35.6% of MDS and only 13.0% of RA/AA, RA/ITP or RA/HA. These results indicated that cytogenetic techniques were useful in hematological clinic and that RA/AA, or RA/ITP or RA/HA might be pre-RA or atypic RA. This was supported by the results of following up on some RA/AA, RA/ITP or RA/HA cases, (2) clonal abnormal karyotypes were found in 64.4% of MDS. The recurrent chromosomal alterations were +8, 20q-, -5/5q-, -7/7q-, similar to those reported in literatures. (3) 16 MDS cases were followed up and 15 MDS with SCD negative, but one with SCD positive developed leukemia in our hospital. It is suggested that change from SCD positive to negative was indicative of malignant transformation of BM cells. This was supported by the results of cytogenetic analysis in RA/AA, RA/ITP, RA, RAEB, RAEBT and leukemias. (4) Because more structural chromosome alterations occur in SCD negative than SCD positive MDS, the numerous chromosome alterations (monosomy) might occur in earliest development of MDS into leukemias.