Information on warfarin

PGx Dosing Guidelines

Annotation of CPIC Guideline for warfarin and CYP2C9,CYP4F2,VKORC1

The updated guideline for pharmacogenetics-guided warfarin dosing is published by the Clinical Pharmacogenetics Implementation Consortium. The recommendations for dosing are for adult and pediatric patients that are specific to continental ancestry, and are based on genotypes from CYP2C9, VKORC1, CYP4F2, and rs12777823.

Annotation of CPNDS Guideline for warfarin and CYP2C9,VKORC1

The Canadian Pharmacogenomics Network for Drug Safety (CPNDS) clinical recommendation group has published guidelines for the use of pharmacogenetic testing for variants in VKORC1 and CYP2C9 in adult and pediatric patients with an indication for warfarin. They recommend testing for the VKORC1 SNP -1639G>A (rs9923231) and the CYP2C9 alleles *2 and *3 in order to better guide warfarin dosage.

PGx Drug Labels

Annotation of FDA Label for warfarin and CYP2C9,PROC,PROS1,VKORC1

On FDA Biomarker List - see whole list on FDA website
Actionable PGx - see definitions

Warfarin (Coumadin) is an anticoagulant used as a prophylaxis and to treat venous thrombosis, pulmonary embolism, thromboembolic complications from atrial fibrillationa and cardiac valve replacement, and to reduce the recurrence of myocardial infarction. Pharmacogenomics-related dosing information for CYP2C9 and VKORC1 variants is provided within the label. The drug label notes that deficiency in protein C (PROC) or protein S (PROS1) have been associated with tissue necrosis following warfarin administration.

Drug labels from sources other than the FDA are available.

PGx Annotations

Clinical Annotation for rs1799853 (CYP2C9); warfarin; (level 1A Dosage)

Level of Evidence Level 1A
Type Dosage
Genes CYP2C9
OMB Race mixed
Race Notes white, black, asian
Variant rs1799853
Variant Annotation
CC Patients with the CC genotype who are treated with warfarin may require an increased dose as compared to patients with the CT or TT genotype. Other genetic and clinical factors may also influence a patient's dose of warfarin.
CT Patients with the CT genotype who are treated with warfarin may require a decreased dose as compared to patients with the CC genotype, but an increased dose compared to patients with TT genotype. Other genetic and clinical factors may also influence a patient's dose of warfarin.
TT Patients with the TT genotype who are treated with warfarin may require a decreased dose as compared to patients with the CT or CC genotype. Other genetic and clinical factors may also influence a patient's dose of warfarin.

Clinical Annotation for rs1057910 (CYP2C9); warfarin; (level 1A Dosage)

Level of Evidence Level 1A
Type Dosage
Genes CYP2C9
OMB Race mixed
Race Notes white, asian, black
Variant rs1057910
Variant Annotation
AA Patients with the AA genotype may require an increased dose of warfarin as compared to patients with the AC or CC genotype. Other genetic and clinical factors may also influence a patient's risk for adverse events.
AC Patients with the AC genotype may require a decreased dose of warfarin as compared to patients with the AA genotype. Other genetic and clinical factors may also influence a patient's risk for adverse events.
CC Patients with the CC genotype may require a decreased dose of warfarin as compared to patients with the AA genotype. Other genetic and clinical factors may also influence a patient's risk for adverse events.

Clinical Annotation for rs9923231 (VKORC1); warfarin; (level 1A Dosage)

Level of Evidence Level 1A
Type Dosage
Genes VKORC1
OMB Race mixed
Variant rs9923231
Variant Annotation
CC Patients with the CC genotype may require an increased dose of warfarin as compared to patients with the CT or TT genotype. Other genetic and clinical factors may also influence a patient's warfarin dose requirement.
CT Patients with the CT genotype may require a decreased dose of warfarin as compared to patients with the CC genotype or an increased dose as compared to patients with the TT genotype. Other genetic and clinical factors may also influence a patient's warfarin dose requirement.
TT Patients with the TT genotype may require a decerased dose of warfarin as compared to patients with the CC or CT genotype. Other genetic and clinical factors may also influence a patient's warfarin dose requirement.

Clinical Annotation for rs2108622 (CYP4F2); warfarin; Hemorrhage, Intracranial Hemorrhages, Myocardial Infarction, Peripheral Vascular Diseases, Thromboembolism and venous thromboembolism (level 1A Dosage)

Level of Evidence Level 1A
Type Dosage
Genes CYP4F2
Phenotypes Hemorrhage, Intracranial Hemorrhages, Myocardial Infarction, Peripheral Vascular Diseases, Thromboembolism, venous thromboembolism
OMB Race mixed
Race Notes Studies include White, Black or African American, Asian, Hispanic or Latino and Mixed populations.
Variant rs2108622
Variant Annotation
CC Patients with the CC genotype who are treated with warfarin may require a lower dose as compared to patients with the TT genotype. However, this is contradicted in some studies. Other genetic and clinical factors may also influence a patient's required warfarin dose.
CT Patients with the CT genotype who are treated with warfarin may require a lower dose as compared to patients with the TT genotype. However, this is contradicted in some studies. Other genetic and clinical factors may also influence a patient's required warfarin dose.
TT Patients with the TT genotype who are treated with warfarin may require a higher dose as compared to patients with the CC and CT genotypes. However, this is contradicted in some studies. Other genetic and clinical factors may also influence a patient's required warfarin dose.

Clinical Annotation for CYP2C9*1, CYP2C9*2, CYP2C9*3; warfarin; Cardiovascular Diseases and Heart Diseases (level 1A Dosage)

Level of Evidence Level 1A
Type Dosage
Genes CYP2C9
Phenotypes Cardiovascular Diseases, Heart Diseases
OMB Race mixed
Variant CYP2C9*1, CYP2C9*2, CYP2C9*3
Variant Annotation
*1/*1 Patients with the *1/*1 diplotype may require a higher dose of warfarin as compared to patients with the *2 or *3 CYP2C9 alleles. CYP2C9*1/*1 is considered a fully functional genotype. Other genetic and clinical factors may also influence a patient's required dose of warfarin.
*1/*2 Patients with the *1/*2 diplotype may require a lower dose of warfarin as compared to patients with the *1/*1 diplotype. Other genetic and clinical factors may also influence a patient's required dose of warfarin.
*1/*3 Patients with the *1/*3 diplotype may require a lower dose of warfarin as compared to patients with the *1/*1 diplotype. Other genetic and clinical factors may also influence a patient's required dose of warfarin.
*2/*2 Patients with the *2/*2 diplotype may require a lower dose of warfarin as compared to patients with the *1/*1 diplotype. Other genetic and clinical factors may also influence the dose of warfarin.
*2/*3 Patients with the *2/*3 diplotype may require a lower dose of warfarin as compared to patients with the *1/*1 diplotype. Other genetic and clinical factors may also influence a patient's required dose of warfarin.
*3/*3 Patients with the *3/*3 diplotype may require a lower dose of warfarin as compared to patients with the *1/*1 diplotype. Other genetic and clinical factors may also influence a patient's required dose of warfarin.

Clinical Annotation for rs7294 (VKORC1); warfarin; (level 1B Dosage)

Level of Evidence Level 1B
Type Dosage
Genes VKORC1
OMB Race mixed
Race Notes White, Asian, Black, Mixed Population
Variant rs7294
Variant Annotation
CC Patients with the CC genotype who are treated with warfarin may require a lower dose as compared to patients with the TC or TT genotype. Other genetic and clinical factors may also influence a patient's required dose of warfarin.
CT Patients with the CT genotype who are treated with warfarin may require a higher dose as compared to patients with the CC genotype. Other genetic and clinical factors may also influence a patient's required dose of warfarin.
TT Patients with the TT genotype who are treated with warfarin may require a higher dose as compared to patients with the CC genotype. Other genetic and clinical factors may also influence a patient's required dose of warfarin.

Clinical Annotation for rs9934438 (VKORC1); warfarin; Arteriosclerosis, Heart Diseases, Hemorrhage, Intracranial Hemorrhages, Myocardial Infarction, Peripheral Vascular Diseases, Pulmonary Embolism, Stroke, Thromboembolism, venous thromboembolism and Venous Thrombosis (level 1B Dosage)

Level of Evidence Level 1B
Type Dosage
Genes VKORC1
Phenotypes Arteriosclerosis, Heart Diseases, Hemorrhage, Intracranial Hemorrhages, Myocardial Infarction, Peripheral Vascular Diseases, Pulmonary Embolism, Stroke, Thromboembolism, venous thromboembolism, Venous Thrombosis
OMB Race mixed
Race Notes White,Black or African American, Asian
Variant rs9934438
Variant Annotation
AA Patients with the AA genotype who are treated with warfarin may require a lower dose as compared to patients with the AG or GG genotype. Other genetic and clinical factors may also influence a patient's required dose of warfarin.
AG Patients with the AG genotype who are treated with warfarin may require a lower dose as compared to patients with the GG genotype, and a higher dose as compared to patients with the AA genotype. Other clinical and genetic factors may also influence a patient’s required dose of warfarin.
GG Patients with the GG genotype who are treated with warfarin may require higher dose as compared to patients with the AG or AA genotype. Other genetic and clinical factors may also influence a patient's required dose of warfarin.

Clinical Annotation for rs7900194 (CYP2C9); warfarin; Atrial Fibrillation, Pulmonary Embolism, Stroke and Venous Thrombosis (level 2A Dosage, Toxicity/ADR)

Level of Evidence Level 2A
Type Dosage, Toxicity/ADR
Genes CYP2C9
Phenotypes Atrial Fibrillation, Pulmonary Embolism, Stroke, Venous Thrombosis
OMB Race Black or African American
Variant rs7900194
Variant Annotation
AA Patients with the AA genotype who are treated with warfarin may require the lowest maintenance dose as compared to patients with the AG or GG genotype. Other clinical or genetic factors may also influence warfarin dose.
AG Patients with the AG genotype who are treated with warfarin may require a lower maintenance dose as compared to patients with the GG genotype. Other clinical or genetic factors may also influence warfarin dose.
GG Patients with the GG genotype who are treated with warfarin may require a higher maintenance dose as compared to patients with the AG or GG genotype. Other clinical or genetic factors may also influence warfarin dose.

Clinical Annotation for rs7089580 (CYP2C9); warfarin; (level 2A Dosage)

Level of Evidence Level 2A
Type Dosage
Genes CYP2C9
OMB Race Black or African American
Variant rs7089580
Variant Annotation
AA Patients with the AA genotype may require lower dose of warfarin as compared to patients with the TT genotype. Other genetic and clinical factors may also influence a patient's warfarin dose.
TA Patients with the TA genotype may require higher dose of warfarin as compared to patients with the AA genotype. Other genetic and clinical factors may also influence a patient's warfarin dose.
TT Patients with the TT genotype may require higher dose of warfarin as compared to patients with the AA genotype. Other genetic and clinical factors may also influence a patient's warfarin dose.

Clinical Annotation for rs4917639 (CYP2C9); warfarin; (level 2A Dosage)

Level of Evidence Level 2A
Type Dosage
Genes CYP2C9
OMB Race Asian, European
Race Notes White, Asian
Variant rs4917639
Variant Annotation
AA Patients with the AA genotype may require increased dose of warfarin as compared to patients with the CC or CA genotype. Other clinical or genetic factors may also influence warfarin dose.
CA Patients with the CA genotype may require decreased dose of warfarin as compared to patients with the AA genotype. Other clinical or genetic factors may also influence warfarin dose.
CC Patients with the CC genotype may require decreased dose of warfarin as compared to patients with the AA genotype. Other clinical or genetic factors may also influence warfarin dose.

Clinical Annotation for rs1057910 (CYP2C9); acenocoumarol or warfarin; Hemorrhage (level 2A Toxicity/ADR)

Level of Evidence Level 2A
Type Toxicity/ADR
Genes CYP2C9
Phenotypes Hemorrhage
OMB Race mixed
Variant rs1057910
Variant Annotation
AA The AA (CYP2C9 *1/*1) genotype may be associated with a decreased risk of hemorrhage when treated with acenocoumarol or warfarin as compared to the CC or AC genotypes, although this is contradicted in most studies. Other clinical and genetic factors may also influence risk of hemorrhage in patients treated with acenocoumarol or warfarin.
AC The AC (CYP2C9 *1/*3) genotype may be associated with a decreased risk of hemorrhage when treated with acenocoumarol or warfarin as compared to the CC and an increased risk as compared to the AA genotype, although this is contradicted in most studies. Other clinical and genetic factors may also influence risk of hemorrhage in patients treated with acenocoumarol or warfarin.
CC The CC (CYP2C9 *3/*3) genotype may be associated with an increased risk of hemorrhage when treated with acenocoumarol or warfarin as compared to the AA or AC genotypes, although this may be contradicted in most studies. Other clinical and genetic factors may also influence risk of hemorrhage in patients treated with acenocoumarol or warfarin.

Clinical Annotation for rs56165452 (CYP2C9); warfarin; (level 2A Dosage)

Level of Evidence Level 2A
Type Dosage
Genes CYP2C9
OMB Race mixed
Race Notes Black, White, Asian
Variant rs56165452
Variant Annotation
CC Patients with the CC genotype may required reduced dose of warfarin as compared to patients with the TT genotype. Other clinical or genetic factors may also influence warfarin dose. This variant rs56165452 defines CYP2C9*4.
CT Patients with the CT genotype may required reduced dose of warfarin as compared to patients with the TT genotype. Other clinical or genetic factors may also influence warfarin dose. This variant rs56165452 defines CYP2C9*4.
TT Patients with the TT genotype may required higher dose of warfarin as compared to patients with the CT or CC genotype. Other clinical or genetic factors may also influence warfarin dose. This variant rs56165452 defines CYP2C9*4.

Clinical Annotation for rs28371686 (CYP2C9); warfarin; Atrial Fibrillation, Pulmonary Embolism, Stroke and Venous Thrombosis (level 2A Dosage)

Level of Evidence Level 2A
Type Dosage
Genes CYP2C9
Phenotypes Atrial Fibrillation, Pulmonary Embolism, Stroke, Venous Thrombosis
OMB Race Black or African American
Variant rs28371686
Variant Annotation
CC Patients with the CC genotype who are treated with warfarin may require an increased dose as compared to patients with the CG and GG genotype. Other genetic and clinical factors may also influence a patient's required dose of warfarin.
CG Patients with the CG genotype who are treated with warfarin may require a decreased dose as compared to patients with CC genotype. Other genetic and clinical factors may also influence a patient's required dose of warfarin.
GG Patients with the GG genotype who are treated with warfarin may require the lowest dose as compared to patients with the CG or CC genotype. Other genetic and clinical factors may also influence a patient's required dose of warfarin.

Clinical Annotation for rs2359612 (VKORC1); warfarin; (level 2A Dosage)

Level of Evidence Level 2A
Type Dosage
Genes VKORC1
OMB Race mixed
Race Notes Asians, Black or Whites
Variant rs2359612
Variant Annotation
AA Patients with the AA genotype who are treated with warfarin may require a decreased dose as compared to patients with the GG genotype. Other genetic and clinical factors may also influence dose of warfarin.
AG Patients with the AG genotype who are treated with warfarin may require a decreased dose as compared to patients with the GG genotype. Other genetic and clinical factors may also influence dose of warfarin.
GG Patients with the GG genotype who are treated with warfarin may require an increased dose as compared to patients with the AG or AA genotype. Other genetic and clinical factors may also influence dose of warfarin.

Clinical Annotation for rs8050894 (VKORC1); warfarin; (level 2A Dosage)

Level of Evidence Level 2A
Type Dosage
Genes VKORC1
OMB Race mixed
Race Notes Asians, Black or Whites
Variant rs8050894
Variant Annotation
CC Patients with the CC genotype who are treated with warfarin may require a higher dose as compared to patients with the CG or GG genotype. Other genetic and clinical factors may also influence a patient's required dose of warfarin.
CG Patients with the CG genotype who are treated with warfarin may require a lower dose as compared to patients with the CC genotype. Other genetic and clinical factors may also influence a patient's required dose of warfarin.
GG Patients with the GG genotype who are treated with warfarin may require the lowest dose as compared to patients with the CC genotype. Other genetic and clinical factors may also influence a patient's required dose of warfarin.

Clinical Annotation for rs17708472 (VKORC1); warfarin; (level 2A Dosage)

Level of Evidence Level 2A
Type Dosage
Genes VKORC1
OMB Race European
Variant rs17708472
Variant Annotation
AA Patients with the AA genotype (homozygous for VKORC1*4) may require a higher dose of warfarin as compared to patients with the GG genotype. Some studies have not found a significant association between this variant and warfarin dose, however the majority report an association. Other genetic and clinical factors may also influence a patient's required dose of warfarin.
AG Patients with the AG genotype (heterozygous for VKORC1*4) may require a higher dose of warfarin as compared to patients with the GG genotype. Some studies have not found a significant association between this variant and warfarin dose, however the majority report an association. Other genetic and clinical factors may also influence a patient's required dose of warfarin.
GG Patients with the GG genotype may require a lower dose of warfarin as compared to patients with the AG and AA genotype. Some studies have not found a significant association between this variant and warfarin dose, however the majority report an association. Other genetic and clinical factors may also influence a patient's required dose of warfarin.

Clinical Annotation for rs2884737 (VKORC1); warfarin; (level 2A Dosage)

Level of Evidence Level 2A
Type Dosage
Genes VKORC1
OMB Race mixed
Race Notes white, black, South Indian
Variant rs2884737
Variant Annotation
AA Patients with the AA genotype may require higher dose of warfarin as compared to patients with the CC genotype. Other clinical and genetic factors may also influence a patient's warfarin dose.
AC Patients with the AC genotype may require higher dose of warfarin as compared to patients with the CC genotype. Other clinical and genetic factors may also influence a patient's warfarin dose.
CC Patients with the CC genotype may require lower dose of warfarin as compared to patients with the AA genotype. Other clinical and genetic factors may also influence a patient's warfarin dose.

Clinical Annotation for rs61742245 (VKORC1); warfarin; (level 2A Dosage)

Level of Evidence Level 2A
Type Dosage
Genes VKORC1
OMB Race European
Variant rs61742245
Variant Annotation
AA Patients with the AA genotype may have increased dose of warfarin as compared to patients with genotype CC. Other genetic and clinical factors may also influence the dose of warfarin.
AC Patients with the AC genotype may have increased dose of warfarin as compared to patients with genotype CC. Other genetic and clinical factors may also influence the dose of warfarin.
CC Patients with the CC genotype may have decreased dose of warfarin as compared to patients with genotype AA or AC. Other genetic and clinical factors may also influence the dose of warfarin.

Clinical Annotation for rs9923231 (VKORC1); warfarin; (level 2A Efficacy)

Level of Evidence Level 2A
Type Efficacy
Genes VKORC1
OMB Race mixed
Variant rs9923231
Variant Annotation
CC Patients with genotype CC may require longer time to therapeutic INR when treated with warfarin as compared with patients with genotype TT or CT. Other genetic and clinical factors may also influence the response to warfarin.
CT Patients with genotype CT may require shorter time to therapeutic INR when treated with warfarin as compared with patients with genotype CC. Other genetic and clinical factors may also influence the response to warfarin.
TT Patients with genotype TT may require shorter time to therapeutic INR when treated with warfarin as compared with patients with genotype CC. Other genetic and clinical factors may also influence the response to warfarin.

Clinical Annotation for rs9923231 (VKORC1); warfarin; over-anticoagulation (level 2A Toxicity/ADR)

Level of Evidence Level 2A
Type Toxicity/ADR
Genes VKORC1
Phenotypes over-anticoagulation
OMB Race mixed
Variant rs9923231
Variant Annotation
CC Patients with the CC genotype may have decreased risk of over-anticoagulation when treated with warfarin as compared with patients with genotype TT or CT. Other genetic and clinical factors may also influence the toxicity to warfarin.
CT Patients with the CT genotype may have increased risk of over-anticoagulation when treated with warfarin as compared with patients with genotype CC. Other genetic and clinical factors may also influence the toxicity to warfarin.
TT Patients with the TT genotype may have increased risk of over-anticoagulation when treated with warfarin as compared with patients with genotype CC. Other genetic and clinical factors may also influence the toxicity to warfarin.

Clinical Annotation for rs9923231 (VKORC1); acenocoumarol, phenprocoumon or warfarin; Atrial Fibrillation, Stroke and venous thromboembolism (level 2A Toxicity/ADR)

Level of Evidence Level 2A
Type Toxicity/ADR
Genes VKORC1
Phenotypes Atrial Fibrillation, Stroke, venous thromboembolism
OMB Race mixed
Variant rs9923231
Variant Annotation
CC Patients with the CC genotype who are treated with warfarin or acenocoumarol may have a decreased risk of Hemorrhage as compared to the CT or TT genotypes, however this is contradicted in nearly half the studies. Other clinical and genetic factors may also influence risk of hemorrhage in patients administered warfarin or acenocoumarol.
CT Patients with the CT genotype who are treated with warfarin or acenocoumarol may have an increased risk of Hemorrhage as compared to the CC genotypes, however this is contradicted in nearly half the studies. Other clinical and genetic factors may also influence risk of hemorrhage in patients administered warfarin or acenocoumarol.
TT Patients with the TT genotype who are treated with warfarin or acenocoumarol may have an increased risk of Hemorrhage as compared to the CC genotypes, however this is contradicted in nearly half the studies. Other clinical and genetic factors may also influence risk of hemorrhage in patients administered warfarin or acenocoumarol.

Clinical Annotation for rs2108622 (CYP4F2); warfarin; over-anticoagulation (level 2A)

Level of Evidence Level 2A
Type Other
Genes CYP4F2
Phenotypes over-anticoagulation
OMB Race mixed
Race Notes Asian, White
Variant rs2108622
Variant Annotation
CC Patients with the CC genotype who are treated with warfarin may have an increased risk of over-coagulation as compared to patients with the TT genotype, although this is contradicted in one study, which found that the CC genotype may have an increased risk versus the CT genotype as well as the TT genotype. Other clinical and genetic factors may also influence risk of over-coagulation in patients administered warfarin.
CT Patients with the CT genotype who are treated with warfarin may have a decreased risk of over-coagulation as compared to patients with the TT genotype, although this is contradicted in one study which found that the CT genotype may have an increased risk of over-coagulation versus the TT genotype. Other clinical and genetic factors may also influence risk of over-coagulation in patients administered warfarin.
TT Patients with the TT genotype who are treated with warfarin may have a decreased risk of over-coagulation as compared to patients with the CT or CC genotype, although this is contradicted in one study which found that it had a decreased risk of over-coagulation as compared only to patients with the CC genotype. Other clinical and genetic factors may also influence risk of over-coagulation in patients administered warfarin.

Clinical Annotation for CYP2C9*1, CYP2C9*11, CYP2C9*2, CYP2C9*3, CYP2C9*5, CYP2C9*6; warfarin; (level 2A Toxicity/ADR)

Level of Evidence Level 2A
Type Toxicity/ADR
Genes CYP2C9
OMB Race mixed
Variant CYP2C9*1, CYP2C9*11, CYP2C9*2, CYP2C9*3, CYP2C9*5, CYP2C9*6
Variant Annotation
*1/*1 Patients with CYP2C9*1/*1 may have decreased risk of over-anticoagulation when treated with warfarin as compared to patients with CYP2C9*2, *3, *5, *6 or *11. Other genetic and clinical factors may also influence the toxicity to warfarin.
*11 Patients with CYP2C9*11 may have increased risk of over-anticoagulation when treated with warfarin as compared to patients with CYP2C9*1/*1. Other genetic and clinical factors may also influence the toxicity to warfarin.
*2 Patients with CYP2C9*2 may have increased risk of over-anticoagulation when treated with warfarin as compared to patients with CYP2C9*1/*1. Other genetic and clinical factors may also influence the toxicity to warfarin.
*3 Patients with CYP2C9*3 may have increased risk of over-anticoagulation when treated with warfarin as compared to patients with CYP2C9*1/*1. Other genetic and clinical factors may also influence the toxicity to warfarin.
*5 Patients with CYP2C9*5 may have increased risk of over-anticoagulation when treated with warfarin as compared to patients with CYP2C9*1/*1. Other genetic and clinical factors may also influence the toxicity to warfarin.
*6 Patients with CYP2C9*6 may have increased risk of over-anticoagulation when treated with warfarin as compared to patients with CYP2C9*1/*1. Other genetic and clinical factors may also influence the toxicity to warfarin.

Clinical Annotation for CYP2C9*1, CYP2C9*2, CYP2C9*3; warfarin; Hemorrhage (level 2A Toxicity/ADR)

Level of Evidence Level 2A
Type Toxicity/ADR
Genes CYP2C9
Phenotypes Hemorrhage
OMB Race mixed
Variant CYP2C9*1, CYP2C9*2, CYP2C9*3
Variant Annotation
*1/*1 Patients with the CYP2C9*1/*1 genotype may have a decreased risk of bleeding when treated with warfarin as compared to patients carrying either CYP2C9*2 or *3, however this is contradicted in several studies. Other genetic and clinical factors may also influence the risk of bleeding in patients administered warfarin.
*1/*2 Patients with the CYP2C9*1/*2 genotype may have increased risk of bleeding when treated with warfarin as compared to patients with CYP2C9*1/*1 genotype, however this is contradicted in several studies. Other genetic and clinical factors may also influence the risk of bleeding in patients administered warfarin.
*1/*3 Patients with CYP2C9*1/*3 genotype may have increased risk of bleeding when treated with warfarin as compared to patients with CYP2C9*1/*1, however this is contradicted in several studies. Other genetic and clinical factors may also influence the risk of bleeding in patients administered warfarin.
*2/*2 Patients with the CYP2C9 *2/*2 genotype may have an increased risk of bleeding when treated with warfarin as compared to patients with the CYP2C9*2/*2 genotype, however this is contradicted in several studies. Other genetic and clinical factors may also influence the risk of bleeding in patients administered warfarin.
*2/*3 Patients with the CYP2C9 *2/*3 genotype may have an increased risk of bleeding when treated with warfarin as compared to patients with the CYP2C9*2/*2 genotype, however this is contradicted in several studies. Other genetic and clinical factors may also influence the risk of bleeding in patients administered warfarin.
*3/*3 Patients with the CYP2C9 *3/*3 genotype may have an increased risk of bleeding when treated with warfarin as compared to patients with the CYP2C9*2/*2 genotype, however this is contradicted in several studies. Other genetic and clinical factors may also influence the risk of bleeding in patients administered warfarin.

Clinical Annotation for rs11676382 (GGCX); warfarin; (level 2B Dosage)

Level of Evidence Level 2B
Type Dosage
Genes GGCX
OMB Race Asian, European
Variant rs11676382
Variant Annotation
CC Patients with the CC genotype may need an increased dose of warfarin as compared to patients with the CG and GG genotypes, however this has been contradicted in some studies. Other clinical and genetic factors may also influence dose of warfarin.
CG Patients with the CG genotype may need a decreased dose of warfarin as compared to patients with the CC genotype, however this has been contradicted in some studies. Other clinical and genetic factors may also influence dose of warfarin.
GG Patients with the GG genotype may need a decreased dose of warfarin as compared to patients with the CC genotype, however this has been contradicted in some studies. Other clinical and genetic factors may also influence dose of warfarin.

Clinical Annotation for rs339097 (CALU); warfarin; (level 2B Dosage)

Level of Evidence Level 2B
Type Dosage
Genes CALU
OMB Race mixed
Variant rs339097
Variant Annotation
AA Patients with the AA genotype who are treated with warfarin may require a lower maintenance dose as compared to patients with the AG or GG genotype, although this is contradicted in one study. Other genetic and clinical factors may also influence a patient's warfarin dose.
AG Patients with the AG genotype who are treated with warfarin may require a higher maintenance dose as compared to patients with the AA genotype, although this is contradicted in one study. Other genetic and clinical factors may also influence a patient's warfarin dose.
GG Patients with the GG genotype who are treated with warfarin may require a higher maintenance dose as compared to patients with the AA genotype, although this is contradicted in one study. Other genetic and clinical factors may also influence a patient's warfarin dose.

Clinical Annotation for rs12777823; warfarin; (level 2B Dosage)

Level of Evidence Level 2B
Type Dosage
OMB Race Black or African American
Variant rs12777823
Variant Annotation
AA Patients with the AA genotype may require a lower dose of warfarin (may require a dose reduction of 9·34 mg/week) in African Americans as compared to patients with the GG genotype. Other genetic and clinical factors may also influence a patient's required dose of warfarin.
AG Patients with the AG genotype may require a lower dose of warfarin (may require a dose reduction of 6·92 mg/week) in African Americans as compared to patients with the GG genotype. Other genetic and clinical factors may also influence a patient's required dose of warfarin.
GG Patients with the GG genotype may require a higher dose of warfarin in African Americans as compared to patients with the AA or AG genotype. Other genetic and clinical factors may also influence a patient's required dose of warfarin.

Clinical Annotation for rs7196161 (VKORC1); warfarin; (level 2B Dosage)

Level of Evidence Level 2B
Type Dosage
Genes VKORC1
OMB Race Asian
Race Notes Asian, South Indian
Variant rs7196161
Variant Annotation
AA Patients with the AA genotype may require an increased dose of warfarin as compared to patients with the AG and GG genotypes. Other clinical and genetic factors may also influence the dose of warfarin.
AG Patients with the AG genotype may require an increased dose of warfarin as compared to patients with the GG genotype and a decreased dose of warfarin as compared to patients with the AA genotype. Other clinical and genetic factors may also influence the dose of warfarin.
GG Patients with the GG genotype may require a decreased dose of warfarin as compared to patients with the AG and AA genotypes. Other clinical and genetic factors may also influence the dose of warfarin.

Clinical annotations with lower levels of evidence are available.


Information on aspirin

PGx Dosing Guidelines

There are no dosing guidelines available.

PGx Drug Labels

There are no drug labels available.

PGx Annotations

Clinical Annotation for rs730012 (LTC4S); aspirin; Urticaria (level 2B Toxicity/ADR)

Level of Evidence Level 2B
Type Toxicity/ADR
Genes LTC4S
Phenotypes Urticaria
OMB Race mixed
Race Notes Mixed (Hispanic or Latino,American Indian or Alaska Native(American Indian), Black or African American)
Variant rs730012
Variant Annotation
AA Patients with the AA genotype who are treated with aspirin may have a decreased, but not absent, risk of urticaria as compared to patients with the AC or CC genotype. Other genetic and clinical factors may also influence a patient's risk for urticaria.
AC Patients with the AC genotype who are treated with aspirin may have an increased risk of urticaria as compared to patients with the AA genotype. Other genetic and clinical factors may also influence a patient's risk for urticaria.
CC Patients with the CC genotype who are treated with aspirin may have an increased risk of urticaria as compared to patients with the AA genotype. Other genetic and clinical factors may also influence a patient's risk for urticaria.

Clinical Annotation for rs10306114 (PTGS1); aspirin; Coronary Artery Disease and Myocardial Infarction (level 2B Efficacy)

Level of Evidence Level 2B
Type Efficacy
Genes PTGS1
Phenotypes Coronary Artery Disease, Myocardial Infarction
OMB Race unknown
Variant rs10306114
Variant Annotation
AA Patients with the AA genotype who are treated with aspirin may have a decreased, but not absent, risk for non-response to aspirin as compared to patients with the AG or GG genotype. Other genetic and clinical factors may also influence a patient's response to aspirin.
AG Patients with the AG genotype who are treated with aspirin may have an increased risk for non-response to aspirin as compared to patients with the AA genotype. Other genetic and clinical factors may also influence a patient's response to aspirin.
GG Patients with the GG genotype who are treated with aspirin may have an increased risk for non-response to aspirin as compared to patients with the AA genotype. Other genetic and clinical factors may also influence a patient's response to aspirin.

Clinical Annotation for rs6065 (GP1BA); aspirin; (level 2B Efficacy)

Level of Evidence Level 2B
Type Efficacy
Genes GP1BA
OMB Race Asian
Variant rs6065
Variant Annotation
CC Patients with the CC genotype may have an increased risk for aspirin resistance as compared to patients with the CT or TT genotype. Other genetic and clinical factors may also influence a patient's response to aspirin.
CT Patients with the CT genotype may have a decreased, but not absent, risk for aspirin resistance as compared to patients with the CC genotype. Other genetic and clinical factors may also influence a patient's response to aspirin.
TT Patients with the TT genotype may have a decreased, but not absent, risk for aspirin resistance as compared to patients with the CC genotype. Other genetic and clinical factors may also influence a patient's response to aspirin.

Clinical Annotation for CYP2C19*1, CYP2C19*17, CYP2C19*2; aspirin and clopidogrel; Cardiovascular Diseases (level 2B Efficacy, Toxicity/ADR)

Level of Evidence Level 2B
Type Efficacy, Toxicity/ADR
Genes CYP2C19
Phenotypes Cardiovascular Diseases
OMB Race mixed
Variant CYP2C19*1, CYP2C19*17, CYP2C19*2
Variant Annotation
*1/*1 Patients with the *1/*1 diplotype may have a decreased incidence of stroke and decreased platelet reactivity, as compared to patients with the *1/*2, or *2/*2 diplotypes. However, this has been contradicted in some studies. Other clinical and genetic factors may also influence patient response to clopidogrel and aspirin.
*1/*17 Patients with the *1/*17 diplotype may have a decreased incidence of stroke, and decreased platelet reactivity, as compared to patients with the *1/*1, *1/*2, or *2/*2 diplotypes. However, this has been contradicted in some studies. Other clinical and genetic factors may also influence patient response to clopidogrel and aspirin.
*1/*2 Patients with the *1/*2 diplotype may have a decreased incidence of stroke decreased platelet reactivity, as compared to patients with the *2/*2 diplotypes, but an increased incidence of stroke and increased platelet reactivity as compared to patients with the *1/*1, *1/*17, or *17/*17 diplotypes. However, this has been contradicted in some studies. Other clinical and genetic factors may also influence patient response to clopidogrel and aspirin.
*17/*17 Patients with the *17/*17 diplotype may have a decreased incidence of stroke and decreased platelet reactivity, as compared to patients with the *1/*2, or *2/*2 diplotypes. However, this has been contradicted in some studies. Other clinical and genetic factors may also influence patient response to clopidogrel and aspirin.
*2/*2 Patients with the *2/*2 diplotype may have an increased incidence of stroke and decreased platelet reactivity, as compared to patients with the *1/*1, *1/*17, *17/*17, *1/*2 diplotypes. However, this has been contradicted in some studies. Other clinical and genetic factors may also influence patient response to clopidogrel and aspirin.

Clinical Annotation for HLA-DPB1*03:01:01; aspirin; Asthma (level 2B Toxicity/ADR)

Level of Evidence Level 2B
Type Toxicity/ADR
Genes HLA-DPB1
Phenotypes Asthma
OMB Race mixed
Race Notes Korean and Unknown
Variant HLA-DPB1*03:01:01
Variant Annotation
*03:01:01 Patients with one or two copies of the HLA-DPB1*03:01:01 allele have an increased risk of asthma when treated with aspirin, as compared to patients with no HLA-DPB1*03:01:01 alleles or negative for the HLA-DPB1*03:01:01 test. Other genetic and clinical factors may also influence a patient's risk of aspirin-induced asthma.

Clinical annotations with lower levels of evidence are available.