Hemophilia B in a female with intellectual disability caused by a deletion of Xq26.3q28 encompassing the F9

摘要

BackgroundHemophilia B is an X‐linked recessive disorder caused by mutations in the F9 on Xq27.1. Mainly males are affected but about 20% of female carriers have clotting factor IX activity below 0.40 IU/ml and bleeding problems. Fragile‐X syndrome (FMR1) and FRAXE syndrome (AFF2) are well‐known causes of X‐linked recessive intellectual disability. Simultaneous deletion of both FMR1 and AFF2 in males results in severe intellectual disability. In females the phenotype is more variable. We report a 19‐year‐old female with severe intellectual disability and a long‐standing bleeding history.