An identical translocation between chromosome 1 and 7 in three patients with myelofibrosis and myeloid metaplasia.

An identical chromosome abnormality was observed in three unrelated patients with meylofibrosis and myeloid metaplasia, two of the patients showing a history of polycythaemia vera (PV) before development of the myelofibrosis. Unstimulated peripheral blood cultures showed a translocation between chromosomes 1 and 7 replacing a homologue of pair 7. It was identified by G- and C-banding as t(1;7)(7pter leads to 7p11::1p1? leads to 1qter). While the first patient also showed trisomy 21 and the third patient had some extra material on the short arm of chromosome 17, all three had trisomy 1q and monosomy 7q. Although each of these abnormalities is frequently observed separately in various haematological disorders, the combination of the two in the form of an identical translocation in three patients is an example of induced non-random cytogenetic change in myelofibrosis.