High telomerase activity in granulocytes from clonal polycythemia vera and essential thrombocythemia.

Essential thrombocythemia (ET) and polycythemia vera (PV) are chronic myeloproliferative disorders that share the involvement of a multipotent progenitor cell and dominance of the transformed clone over normal hematopoiesis. On the other hand, the heterogeneity of these diseases with respect to clonal development from a common progenitor has been well established. To identify useful prognostic indicators, we analyzed telomerase activity (TA), a known marker of neoplastic proliferation, in granulocytes (PMNs) and mononuclear cells (MNCs) from 22 female patients with ET and PV. Clonality status was determined by investigation of X chromosome inactivation patterns (XCIPs). We found a statistically significant positive correlation between high TA and monoclonal pattern of XCIP. Therefore, our data suggest that the use of multiple tumor markers may contribute to a better understanding of the deregulated physiology of these disorders and provide useful prognostic factors.