Haemoglobinopathia Ypsilanti - A rare, but important differential diagnosis to polycythaemia vera.

We present a case of a mother and daughter who were initially diagnosed with polycythaemia vera and treated with venesectio. As JAK2 V6217F/exon 12 mutation analyses became available, these were performed and turned out negative. Haemoglobin electrophoresis was performed and the patients were found to have high oxygen affinity haemoglobin Ypsilanti. It is important and relevant to look for high oxygen affinity variants of haemoglobin when there is a family history of erythrocytosis, in young persons and when there is no apparent reason or clonal marker present.