Heterogeneity of clonal development in chronic myeloproliferative disorders

Recent reports have suggested a previously unexpected variability in the ex pression of the dominant neoplastic clone in myeloproliferative disorders ( MPD). We evaluated 49 female patients with MPD and informative at the X-lin ked androgen receptor (AR) locus to establish the X chromosome inactivation pattern of hemopoietic cells. Whereas in chronic myelogenous leukemia (CML ) the granulocytes (PMN) were uniformly of mono-clonal origin, a striking h eterogeneity of clonal development was found in PMN from patients with othe r MPD, with up to 50% of them expressing a polyclonal pattern of X inactiva tion. (C) 1999 Wiley-Liss, Inc.