Table 2.

Description and prevalence of genotypes with CPIC guidelines^{6–8, 15}

Allele	Genetic polymorphism	Prevalence
CYP2C9*2	Nonsynonymous SNP (Arg144Gly) leading to decreased enzyme activity	Present in approximately 25% of Europeans and 5% of African Americans. Usually absent in Asians.
CYP2C9*3	Nonsynonymous SNP (Ile359Leu) leading to decreased enzyme activity	Present in approximately 12% of Europeans, 8% of Asians, and 2% of African Americans
CYP2C9*5	Nonsynonymous SNP (Asp360Glu) leading to decreased enzyme activity	Present in 1–2% of African Americans. Usually absent in Europeans and Asians.
CYP2C9*6	Frameshift mutation leading to decreased enzyme activity	Present in about 1% of African Americans. Usually absent in Europeans and Asians.
CYP2C9*8	Nonsynonymous SNP (Arg150His) leading to decreased enzyme activity	Present in about 12% of African Americans. Usually absent in Europeans and Asians.
CYP2C9*11	Nonsynonymous SNP (Arg335Trp) leading to decreased enzyme activity	Present in about 3% of African Americans and <1% of Europeans and Asians.
VKORC1 -1639G>A	SNP in the gene regulatory region affecting gene expression	Approximately 48% of Europeans, 16% of Asians, and 20% of African Americans have the AG genotype. Approximately 15% of Europeans, 83% of Asians, and 2% of African Americans have the AA genotype.
CYP2C19*2	Splicing defect leading to loss of activity	Approximately 25–30% of Europeans and African Americans and 50% of Asians have the *2 allele.
SLCO1B1 521T>C	Nonsynonymous SNP	Approximately 10 to 35% of individuals carry a single 521C allele, and up to 6% have the CC genotype.