Clinical Significance of Cytogenetics in Myeloproliferative Disorders

A complicating feature of the myeloproliferative disorders is the frequent overlap of clinical, laboratory, and morphologic findings among the specific disorders. Cytogenetic and/or fluorescence in situ hybridization studies are performed to obtain evidence of abnormal clones, classify disease, and assess prognosis. These studies help to establish which hematopoietic compartments are affected. For chronic myelogenous leukemia, the BCR/ABL fusion gene allows an unequivocal diagnosis when it occurs with characteristic morphologic and clinical findings. Another activated fusion tyrosine kinase (FIP1L1-PDGFRA) has been recently identified in chronic eosinophilic leukemia/hypereosinophilic syndrome. In contrast, no specific chromosomal or molecular markers have been identified for the remaining MPD, although recurring cytogenetic abnormalities have been reported. In this review, we discuss the cytogenetic anomalies and their associated clinical significance in myeloproliferative disorders.