Molecular classification and pathogenesis of eosinophilic disorders: 2005 update.
Use of the term "idiopathic hypereosinophilic syndrome (HES)" has highlighted our basic lack of understanding of the molecular pathophysiology of eosinophilic disorders. However, over the last 10 years, the study of hypereosinophilia has enjoyed a revival. This interest has been rekindled by two factors: (1) the development of increasingly sophisticated molecular biology techniques that have unmasked recurrent genetic abnormalities linked to eosinophilia, and (2) the successful application of targeted therapy with agents such as imatinib to treat eosinophilic diseases. To date, most of these recurrent molecular abnormalities have resulted in constitutively activated fusion tyrosine kinases whose phenotypic consequence is an eosinophilia-associated myeloid disorder. Most notable among these are rearrangements of platelet-derived growth factor receptors alpha and beta (PDGFRalpha, PDGFRbeta), which define a small subset of patients with eosinophilic chronic myeloproliferative disorders (MPDs) and/or overlap myelodysplastic syndrome/MPD syndromes, including chronic myelomonocytic leukemia. Discovery of the cryptic FIP1L1-PDGFRA gene fusion in cytogenetically normal patients with systemic mast cell disease with eosinophilia or idiopathic HES has redefined these diseases as clonal eosinophilias. A growing list of fibroblast growth factor receptor 1 fusion partners has similarly emerged in the 8p11 myeloproliferative syndromes, which are often characterized by elevated eosinophil counts. Herein the focus is on the molecular gains made in these MPD-type eosinophilias, and the classification and clinicopathological issues related to hypereosinophilic syndromes, including the lymphocyte variant. Success in establishing the molecular basis of a group of once seemingly heterogeneous diseases has now the laid the foundation for establishing a semi-molecular classification scheme of eosinophilic disorders.
Gotlib
Jason
J
Stanford Cancer Center, 875 Blake Wilbur Drive, Rm. 2327B, Stanford, CA 94305-5821, USA. jason.gotlib@stanford.edu
D006801:Humans; D017681:Hypereosinophilic Syndrome / Q000145:classification* / Q000235:genetics / Q000473:pathology; D015477:Leukemia, Myelomonocytic, Chronic / Q000145:classification / Q000235:genetics / Q000473:pathology; D034721:Mastocytosis, Systemic / Q000145:classification* / Q000235:genetics / Q000473:pathology; D009196:Myeloproliferative Disorders / Q000145:classification / Q000235:genetics / Q000473:pathology; D015514:Oncogene Proteins, Fusion / Q000235:genetics*; D011518:Proto-Oncogene Proteins / Q000235:genetics; D020796:Receptor, Platelet-Derived Growth Factor alpha / Q000235:genetics; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000235:genetics; D014178:Translocation, Genetic / Q000235:genetics; D039221:mRNA Cleavage and Polyadenylation Factors / Q000235:genetics
C117597:CEP43 protein, human; D015514:Oncogene Proteins, Fusion; D011518:Proto-Oncogene Proteins; D039221:mRNA Cleavage and Polyadenylation Factors; C479819:FIP1L1-PDGFRA fusion protein, human; D020796:Receptor, Platelet-Derived Growth Factor alpha; D020797:Receptor, Platelet-Derived Growth Factor beta