No abstract

Warfarin is a commonly prescribed anticoagulant drug for the prevention of thromboembolic disorders. We investigated the contribution of genetic variations of four genes and clinical factors to warfarin dose requirement and provided a warfarin-dosing algorithm based on genetic and clinical variables in Korean patients. We recruited 564 Korean patients on stable anticoagulation. Single nucleotide polymorphisms (SNPs) for the VKORC1, CYP2C9, CYP4F2 and GGCX were analyzed. Using multiple regression analysis, we developed a model to predict the warfarin requirement. The SNPs of VKORC1, CYP2C9, CYP4F2 and GGCX showed significant correlation with warfarin dose. Patients with the 3730AA genotype received significantly higher doses of warfarin than those with the 3730GG (P¼0.0001). For CYP2C9, the highest maintenance dose was observed in the patients with wild-type genotype compared with the variant allele carriers (Po0.0001). The multiple regression model including age, gender, body surface area (BSA), international normalized ratio (INR) and four genetic polymorphisms accounted for 35% of total variations in warfarin dose (R 2 ¼0.3499; Po0.0001). This study shows that age, gender, BSA, INR and VKORC1, CYP2C9 and CYP4F2 polymorphism affect warfarin dose requirements in Koreans. Translation of this knowledge into clinical guidelines for warfarin prescription may contribute to improve the efficacy and safety of warfarin treatment for Korean patients.

(Heart 1999;82:415-419)

Myeloproliferative neoplasms (MPNs) are classified as chronic myeloid leukemia (CML) and Philadelphia chromosome-negative MPN. In MPN cases, the presence of a <i>BCR-ABL1</i> translocation with a coexisting mutation is exceptionally rare. Herein, we report the first documented patient with CML harboring <i>CALR</i> mutation in Korea. A 33-year-old woman was referred to our hospital in February 2015 with splenomegaly, leukocytosis, and thrombocytosis. She was diagnosed with CML and started receiving nilotinib. In October 2015, a major molecular response was observed, but thrombocytosis persisted. A repeat bone marrow (BM) examination revealed no specific findings. However, as thrombocytosis worsened, we changed nilotinib to dasatinib. In May 2019, owing to persistent thrombocytosis, we repeated the BM examination and found <i>CALR</i> mutation (15.97%) on the MPN–next generation sequencing (NGS) test. We then retrospectively performed repeat MPN-NGS testing using the BM aspirate sample obtained in 2015 and found <i>CALR</i> mutation (10.64%).