PROS1 and paroxysmal nocturnal hemoglobinuria: Recent studies have reported that the risk factors for BCS include Leiden mutation of Factor V, prothrombin G20210A mutation, inherited protein C, protein S, or antithrombin deficiencies, myeloproliferative neoplasms (MPNs) caused by gene mutations of JAK2V617F,6CALR,7 or MPLW515L,8 and paroxysmal nocturnal hemoglobinuria (PNH).9