Abstract
Hemophilia B is a hereditary bleeding disorder caused by quantitative or qualitative abnormalities in coagulation factor IX. To determine the molecular defects in 20 Japanese patients from 20 families, we amplified and sequenced all the exons, their splice junctions, and the 5' flanking region of the factor IX gene. Eighteen different mutations (11 missense, 4 nonsense, and 3 splice site mutations) were identified in samples from the 20 patients. No deletion or insertion mutation was detected. Four mutations, Ala28 → Pro, Gln50 → Lys, Leu300 → Pro, and A → C transversion at the donor splice site of intron 7, have not been reported previously. To date, 896 genetic defects have been registered in the international hemophilia B mutation database. These findings suggest that more hemophilia B mutations are to be identified in the future.
