Peripheral circulating cells with paroxysmal nocturnal haemoglobinuria phenotype after a first episode of cerebral sinus vein thrombosis: Results from a multicentre cross-sectional study

Paroxysmal nocturnal haemoglobinuria (PNH) is a rare, potentially fatal disorder of haematopoietic stem cells caused by mutations in an X-linked gene called phosphatidylinositol glycan class A, characterised by intravascular haemolysis, bone marrow failure and thrombotic events. The disease can occur at any age, although preferentially it affects young adults; its estimated prevalence is about 1/500,000 [1]. Clinical symptoms are variable and can include haemolytic anaemia, moderate to severe impairment of haematopoiesis and, in approximately 40% of patients, thrombosis of the vessels of the abdomen, brain and skin [2]. Rare, atypical site thrombosis of the splanchnic veins or cerebral sinuses are recognized as suggestive of the presence of a PNH clone [3]. To date, however, the prevalence of PNH clones in unselected patients with cerebral venous thrombosis is not yet known. The primary objective of this study was to determine the prevalence of PNH clones in patients with a recent history of cerebral sinus venous thrombosis (CSVT) and up to twenty-four months follow-up. In this multicentre cross-sectional study, patients with an objective diagnosis of CSVT of new onset or occurring in the previous three years were investigated for the presence of PNH clones. Known or clinically suspected PNH and active treatments able to interfere