{{Rsnum
|rsid=1135840
|Gene=CYP2D6
|Chromosome=22
|position=42522613
|Orientation=minus
|ReferenceAllele=C
|MissenseAllele=G
|GMAF=0.4008
|Assembly=GRCh37
|GenomeBuild=37.1
|dbSNPBuild=131
|geno1=(C;C)
|geno2=(C;G)
|geno3=(G;G)
}}
[[rs1135840]], also known as  4180G>C or S486T, is a SNP in the [[CYP2D6]] gene.

The wild type (normal) allele at this SNP is (G). The (C) variant indicates the presence of a non-wild type CYP2D6 variant, but it appears in many different variants so it can not be used to determine the presence of any particular variant. 

Please be careful when interpreting results for this SNP as it is in dbSNP and SNPedia in minus orientation where the risk allele is C, but test results are usually in plus orientation where the risk allele is G. This SNP has an ambiguous flip which can make this very confusing. 

{{PharmGKB
|RSID=rs1135840
|Name_s=CYP2D6:4180G>C, part of CYP2D6*2A an extensive metabolizer haplotype.
|Gene_s=CYP2D6
|Feature=Exon/NonSyn
|Evidence=PubMed ID:20309015
|Annotation=Risk or phenotype-associated allele: T. Phenotype: The CYP2D6*2A haplotype was associated with lower incidence of breast cancer on tamoxifen compared to placebo in a prevention study. The CYP2D6*2A allele may be associated with increased efficacy of tamoxifen. Study size: 182. Study population/ethnicity: Women in the Italian Tamoxifen Prevention trial, Caucasian, Italy. Significance metric(s): p = 0.0001. Type of association: CO.
|Drugs=tamoxifen
|Drug Classes=
|Diseases=Breast Neoplasms
|Curation Level=Curated
|PharmGKB Accession ID=PA165349810
}}

{{PharmGKB
|RSID=rs1135840
|Name_s=CYP2D6: S486T
|Gene_s=CYP2D6
|Feature=Exon/NonSyn
|Evidence=PubMed ID:18839161; PubMed ID:7935325; PubMed ID:8287064
|Annotation=This common SNP is found in the reduced function CYP2D6*10, *17, and *41 haplotypes among others.
|Drugs=
|Drug Classes=
|Diseases=
|Curation Level=Curated
|PharmGKB Accession ID=PA162355760
}}

{{omim
|id=124030
|rsnum=1135840
|variant=0007
}}

{{PMID|18698231|OA=1
}} Polymorphisms affecting gene transcription and mRNA processing in pharmacogenetic candidate genes: detection through allelic expression imbalance in human target tissues.

{{GET Evidence
|gene=CYP2D6
|aa_change=Thr486Ser
|aa_change_short=T486S
|impact=not reviewed
|qualified_impact=Insufficiently evaluated not reviewed
|inheritance=unknown
|quality_scores=Array
|dbsnp_id=rs1135840
|overall_frequency_n=4392
|overall_frequency_d=10732
|overall_frequency=0.409243
|n_genomes=32
|n_genomes_annotated=0
|n_haplomes=39
|n_articles=0
|n_articles_annotated=0
|nblosum100=-2
|autoscore=0
|webscore=N
}}

{{ClinVar
|ALT=C
|CAF=0.5992; 0.4008
|CHROM=22
|CLNALLE=1
|CLNHGVS=NC_000022.10:g.42522613G>C
|CLNSIG=1
|COMMON=1
|FwdALT=G
|FwdREF=C
|REF=G
|RSPOS=42522613
|Reversed=1
|SAO=0
|SSR=0
|Tags=RV;PM;TPA;PMC;SLO;VLD;G5;HD;GNO;KGPhase1;KGPilot123;KGPROD;OTHERKG;LSD;OM
|VC=SNV
|VP=0x05017800000115051e110100
|WGT=1
|dbSNPBuildID=86
|rsid=1135840
}}

{{PMID Auto
|PMID=22722500
|Title=Association study of 27 annotated genes for clozapine pharmacogenetics: validation of preexisting studies and identification of a new candidate gene, ABCB1, for treatment response.
}}

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

{{on chip | 23andMe v2}}
{{on chip | 23andMe v3}}
{{on chip | 23andMe v4}}