Cytogenetic studies in chronic myeloproliferative disorders.

Cytogenetic studies were performed on 113 patients with the clinical diagnosis of a chronic myeloproliferative disorder: 70 were classified as chronic myelocytic leukemia (CML), 8 as polycythemia vera (PV), 10 as osteomyelofibrosis/sclerosis (OMS), and 15 as unclassified myeloproliferative disorder (UMPD). 2 patients, 1 with UMPD and 1 with subacute leukemia, were reclassified as CML after the cytogenetic study. In the group comprising PV, OMS, and UMPD, 28% (9/32) had a chromosomally abnormal clone. The chromosomes affected involved those reported to show nonrandom alterations in myeloproliferative disorders, namely the chromosomes, 1, 7, 8, and 9.4 patients exhibited a loss of the Y-chromosome.