{{Rsnum
|rsid=12248560
|Gene=CYP2C19
|Chromosome=10
|position=96521657
|Orientation=plus
|GMAF=0.1524
|Assembly=GRCh37
|GenomeBuild=37.1
|dbSNPBuild=131
|Summary=Clopidogrel (Plavix®)
|geno1=(C;C)
|geno2=(C;T)
|geno3=(T;T)
}}
{{ population diversity
| geno1=(C;C)
| geno2=(C;T)
| geno3=(T;T)
| CEU | 55.4 | 43.1 | 1.5
| HCB | 95.6 | 4.4 | 0.0
| JPT | 100.0 | 0.0 | 0.0
| YRI | 52.4 | 38.1 | 9.5
| ASW | 0.0 | 0.0 | 0.0
| CHB | 95.6 | 4.4 | 0.0
| CHD | 0.0 | 0.0 | 0.0
| GIH | 0.0 | 0.0 | 0.0
| LWK | 0.0 | 0.0 | 0.0
| MEX | 0.0 | 0.0 | 0.0
| MKK | 0.0 | 0.0 | 0.0
| TSI | 0.0 | 0.0 | 0.0
| HapMapRevision=28
}}{{CPMC SNP
|link=https://cpmc.coriell.org/Sections/Results/Plavix.aspx?PgId=212
}}

[[rs12248560]](T) defines the CYP2C19*17 allele, an ultra fast metabolizer phenotype of the [[CYP2C19]] gene.

CYP2C19*17 is likely to lead to less effective drug treatment by, for example, proton pump inhibitors (such as [[omeprazole]]) and antidepressants.{{PMID|16413245}}

On the other hand, cancer patients who are CYP2C19*17 carriers are more likely to benefit from [[tamoxifen]] treatment, presumably because they break it down more rapidly into the antiestrogenic metabolites endoxifen and 4-hydroxytamoxifen.{{PMID|18024866}} 

A study of 1,000+ breast cancer patients showed a 0.77x decreased risk of [[breast cancer]] for carriers of a CYP2C19*17 allele (CI: 0.65-0.93, p = 0.005). Analysis of a subgroup of such carriers who were using hormone therapy for ten years or longer showed an even stronger effect (odds ratio 0.57, CI: 0.39-0.83, p = 0.003). The theory is that ultra fast metabolism of estrogen leads to lower estrogen levels and lower breast cancer risk.{{PMID|18521743}}

{{ neighbor
| rsid = 28399504
| distance = 806
}}

{{PharmGKB
|RSID=rs12248560
|Name_s=CYP2C19: -806C>T; CYP2C19*17
|Gene_s=CYP2C19
|Feature=
|Evidence=PubMed ID:20083681
|Annotation=Risk or phenotype-associated allele: T Phenotype: For both C/T (n=546) and T/T (n=76) allele carriers, significantly lower ADP-induced platelet aggregation values were found compared with wild-type homozygotes (C/C; n=902; P=0.039 and P=0.008, respectively). T allele carriage was significantly associated with an increased risk of bleeding. The study concludes that CYP2C19*17 carrier status is significantly associated with enhanced response to clopidogrel and an increased risk of bleeding. Study size: 1524 patients. Study population/ethnicity: patients with coronary artery disease and planned drug-eluting stent placement; pretreatment with 600 mg clopidogrel. Type of association: CO; GN
|Drugs=clopidogrel
|Drug Classes=
|Diseases=Coronary Disease
|Curation Level=Curated
|PharmGKB Accession ID=PA165291880
}}

{{PharmGKB
|RSID=rs12248560
|Name_s=CYP2C19: -806C>T
|Gene_s=CYP2C19
|Feature=
|Evidence=PubMed ID:16413245; PubMed ID:18024866
|Annotation=This promoter variant is part of CYP2C19*17 haplotype, which causes increased acitivity and increased transcription of CYP2C19. Patients carrying this allele may exhibit a lack of response to commonly prescribed dosages of certain proton pump inhibitors (PPIs) and antidepressants, due to ultrarapid clearance of these drugs. CYP2C19*17 carriers are more likely to benifit from tamoxifen treatment.
|Drugs=amitriptyline; citalopram; clomipramine; escitalopram; omeprazole; proguanil; tamoxifen
|Drug Classes=
|Diseases=
|Curation Level=Curated
|PharmGKB Accession ID=PA161615690
}}

{{PharmGKB
|RSID=rs12248560
|Name_s=CYP2C19*17 CYP2C19: -806C>T
|Gene_s=CYP2C19
|Feature=
|Evidence=PubMed ID:20801498
|Annotation=Risk or phenotype-associated allele: T. Phenotype: Patients in the clopidogrel group who had any gain-of-function allele had a higher rate of events of major bleeding than did those without any gain-of-function or loss-of-function alleles. Study size: 5148 patients receiving 75 mg clopidogrel once daily Study population/ethnicity: predominantly white (98%) Significance metric(s): p=0.022 Type of association: GN
|Drugs=clopidogrel
|Drug Classes=
|Diseases=
|Curation Level=Curated
|PharmGKB Accession ID=PA165374699
}}

{{PharmGKB
|RSID=rs12248560
|Name_s=part of CYP2C19*17; CYP2C19:(-806)C>T; CYP2C19: -806C>T
|Gene_s=CYP2C19
|Feature=
|Evidence=PubMed ID:19884907
|Annotation=Risk or phenotype-associated allele: T Phenotype: The CYP2C19*17 allele was associated with significantly increased metabolism of imipramine. Study size: 178 Study population/ethnicity: Psychiatric patients aged 18-65 with a score of greater than or equal to 17 on the Hamilton Rating Scale for Depression. Significance metric(s): p = 0.035 Type of association: PK
|Drugs=imipramine
|Drug Classes=
|Diseases=
|Curation Level=Curated
|PharmGKB Accession ID=PA165110646
}}
{{PMID Auto
|PMID=21247447
|Title=CYP2C19 and ABCB1 gene polymorphisms are differently distributed according to ethnicity in the Brazilian general population
|OA=1
}}

{{PMID Auto
|PMID=17048007
|Title=Association of warfarin dose with genes involved in its action and metabolism.
|OA=1
}}

{{PMID Auto
|PMID=19136640
|Title=Rapid identification of the hepatic cytochrome P450 2C19 activity using a novel and noninvasive [13C]pantoprazole breath test.
|OA=1
}}

{{PMID Auto
|PMID=21071160
|Title=Analysis of 50 SNPs in CYP2D6, CYP2C19, CYP2C9, CYP3A4 and CYP1A2 by MALDI-TOF mass spectrometry in Chinese Han population.
}}

{{PMID Auto
|PMID=21172166
|Title=Pharmacogenetics of antidepressant response.
|OA=1
}}

{{GET Evidence
|impact=pharmacogenetic
|qualified_impact=Insufficiently evaluated pharmacogenetic
|inheritance=unknown
|quality_scores=Array
|dbsnp_id=rs12248560
|overall_frequency_n=25
|overall_frequency_d=128
|overall_frequency=0.195312
|n_genomes=25
|n_genomes_annotated=0
|n_haplomes=27
|n_articles=2
|n_articles_annotated=0
|in_pharmgkb=Y
|autoscore=1
|webscore=N
}}

[[Clopidogrel Efficacy]]

{{PMID Auto
|PMID=24380239
|Title=Characterization of the most common CYP2C9 and CYP2C19 allelic variants in the population from the Republic of Macedonia
}}

{{PMID Auto
|PMID=23133420
|Title=Pharmacogenomic Diversity among Brazilians: Influence of Ancestry, Self-Reported Color, and Geographical Origin.
|OA=1
}}

{{PMID Auto
|PMID=24519754
|Title=CYP2C19 genotype-phenotype discordance in patients with multiple myeloma leads to an acquired loss of drug-metabolising activity
}}
{{on chip | 23andMe v2}}
{{on chip | 23andMe v3}}
{{on chip | 23andMe v4}}