The Genetic Heterogeneity of Hemophilia B

Abstract

At least three genetic variants of hemophilia B exist: a variant with positive crossreacting material associated with a normal oxbrain prothrombin time; one with positive material but with prolonged ox-brain prothrombin time; and one with undetectable or reduced material associated with a normal ox-brain prothrombin time. All hemophilia B_M variants appear to have positive cross-reacting material, but it is not clear whether all patients with positive material are identical to the hemophilia B_M variants. Our studies indicate that they are not identical since some patients with positive cross-reacting material have normal ox-brain prothrombin time. The data suggest that hemophilia B is genetically heterogeneous.