The CYP2C9*1 allele is assigned as a normal function allele by CPIC. Patients carrying CYP2C9*1 allele in combination with another normal function allele may have a decreased risk of bleeding when treated with acenocoumarol as compared to patients carrying at least one copy of a decreased function or no function allele. However, conflicting evidence has been reported. This drug-variant pair has been assigned a 鈥渘o recommendation鈥?by DPWG, as it was determined to be not clinically actionable.Other genetic and clinical factors may also influence the risk of bleeding when treated with acenocoumarol.