Figure 2. Dosing recommendations for Warfarin dosing based on genotype for adult patients.

^a“Dose clinically” means to dose without genetic information, which may include use of a clinical dosing algorithm or standard dose approach

^bData strongest for European and East Asian ancestry populations and consistent in other populations.

^c45-50% of individuals with self-reported African ancestry carry CYP2C9*5,*6,*8,*11, or rs12777823. IF CYP2C9*5, *6, *8, and *11 WERE NOT TESTED, DOSE WARFARIN CLINICALLY. Note: these data derive primarily from African Americans, who are largely from West Africa. It is unknown if the same associations are present for those from other parts of Africa.

^dMost algorithms are developed for the target INR 2-3.

^eConsider an alternative agent in individuals with genotypes associated with CYP2C9 poor metabolism (e.g., CYP2C9*3/*3, *2/*3, *3/*3) or both increased sensitivity (VKORC1 A/G or A/A) and CYP2C9 poor metabolism.

^fSee the EU-PACT trial for pharmacogenetics-based warfarin initiation (loading) dose algorithm (33) with the caveat that the loading dose PG algorithm has not been specifically tested or validated in populations of African ancestry.

^gLarger dose reduction might be needed in variant homozygotes (i.e. 20-40%).

^hAfrican American refers to individuals mainly originating from West Africa.