CYP2C9*61 is assigned decreased function based on limited evidence in a heterozygous patient. CYP2C9*61 was first described in a patient requiring a low daily warfarin dose of 3mg (30518301). CYP2C9*61 is defined by two SNPs, one of which is the defining SNP for CYP2C9*2. Therefore, consensus among experts was decreased function with an activity value of 0.5 based on limited evidence as it was determined the function of this allele is similar to CYP2C9*2 and phenotypes containing this allele would be clinically distinct from phenotypes comprising normal function alleles.