Difference in Fibrin Clot Structure in Haemophilia A and Haemophilia B

Introduction: Hemophilia A and Hemophilia B are X-linked bleeding disorders characterized by deficiency of coagulation factor VIII and IX respectively. The disorders have traditionally been considered to display identical symptoms. However, recent clinical data suggest that hemophilia B has a less severe phenotype than hemophilia A in patients with similar levels of their deficient factor. There is a distinct lack of laboratory studies comparing the hemostatic potential in patients with the same severity grade of Hemophilia A and Hemophilia B. We assessed fibrin clot quality in Hemophilia A and Hemophilia B patient plasma as a possible explanation to the milder bleeding phenotype in patients with Hemophilia B. To achieve this a liquid permeation technique was used, which has been used to investigate fibrin networks in previous in vitro studies (He et. al. Blood Coagul Fibrinolysis 2005). Methods: 20 patients with hemophilia A and 28 with hemophilia B were considered for inclusion in the study. Patients were recruited from centers in Stockholm and Belgrade and were thereafter matched according to their deficient factor level. Hemophilia diagnosis and informed consent formed the basis for study inclusion and exclusion criteria were lack of consent and inability to provide a matched patient from the other group. 17 hemophilia A and 17 hemophilia B patients were included in the study. The patient matching according to factor level was tested with Spearman’s rank-order correlation, yielding a correlation coefficient of 0.999 (p