A myeloproliferative disorder with eosinophilia associated with a unique translocation (3;5).

An association between eosinophilia and a structural chromosome abnormality has been noted in patients with acute non-lymphoblastic leukaemia (ANLL) and a deletion of the long arm of chromosome 16. There have been a number of other associations of specific chromosome abnormalities with neoplastic diseases involving the eosinophilic lineage; these include chromosome 12 short arm rearrangements, trisomy 8, t(8;21), t(5;14) and t(5;12). We report a patient with a myeloproliferative disorder characterized by chronic eosinophilic leukaemia complicated by autoimmune haemolytic anaemia and a previously unreported translocation (3;5)(p13;q13), and discuss the possible contribution of the RASA gene, localized to 5q13.3, to the development of the malignant phenotype.