A 51-year-old woman presented with increased levels of hematocrit, multiple liver, spleen, and left kidney infarctions and ascites; further investigation revealed a JAK2V617F-positive polycythemia vera and the presence of a significant PNH population (more than 90% CD55– CD59– cells among both granulocytes and red blood cells). The gene discussed is CD55; the disease is infarction.