Chromosome studies in polycythemia vera patients.

One hundred thirty-five polycythemia vera (PV) patients (30 untreated by chemotherapy and 105 treated) were studied cytogenetically . The incidence of clonal chromosomal abnormalities was 20.7% (28 patients in nonleukemic phase). The incidence of 20q - was 3.7% (5 patients). The presence of cytogenetically abnormal clones did not allow prediction of the evolution of the disease. In a few cases, abnormal clones disappeared at the time of later studies. Although nonrandom, the majority of clonal chromosomal abnormalities are believed to be secondary events in PV patients.