Individuals are divided into 4 groups according to GGCX genotype. Group 1: 10/10 (CAA) repeats; group 2: 10-11/11 repeats; group 3: 10-11/13 repeats; group 4: 13/13 or x/14-16 repeats. (A) Mean weekly warfarin doses for varying GGCX (CAA) repeats with 95% confidence intervals (groups 1, 2, 3, and 4; ANOVA P = .064). (B) Mean and 95% confidence interval of mean weekly warfarin doses for varying GGCX (CAA) repeats (groups 1-3 combined vs 4; ANOVA P = .011).