A Case of Warfarin-Induced Bleeding in a Patient with CYP2C9 and VKORC1 Gene Polymorphism, Detected by a Point-of-Care Gene Test Device / 대한내과학회지

ABSTRACT

A 69-year-old female Korean patient was initially prescribed warfarin for the prevention of systemic thromboembolism due to atrial fibrillation. One month later, multiple bruises and subcutaneous hematomas were evident, and laboratory testing revealed a prolonged prothrombin time (PT) of > 106s. After admission, the PT was corrected via fresh frozen plasma transfusion and intravenous vitamin K infusion. We sought to determine the cause of the PT prolongation, suspecting that genetic cause may have had an effect on the variation in the warfarin dose requirement. A point-of-care gene test device (Verigene(R) system; Nanosphere, Northbrook, IL) revealed CYP2C9*1/*3 heterozygosity and a VKORC1 A/A single nucleotide polymorphism. Although it is well established that CYP2C9 or VKORC1 gene polymorphisms can influence warfarin dose requirements, they can be easily neglected, with detrimental outcomes. Through our experience with CYP2C9 and VKORC1 polymorphism causing bleeding complications during warfarin treatment, we aim to emphasize the importance of pharmacogenetic testing to avoid this potential oversight.