{{Rsnum
|rsid=1057868
|Gene=POR
|Chromosome=7
|position=75985688
|Orientation=plus
|GMAF=0.2879
|Assembly=GRCh38
|GenomeBuild=38.1
|dbSNPBuild=141
|geno1=(C;C)
|geno2=(C;T)
|geno3=(T;T)
|Gene_s=POR
}}[[rs1057868]], also known as A503V, is a relatively common variant defining the POR*28 allele of the P450 (cytochrome) oxidoreductase [[POR]] gene. The POR gene encodes a protein involved in electron transport of cytochrome p450 enzymes such as [[CYP3A4]], [[CYP3A5]] and [[CYP3A7]].

A study of 251 individuals from two independent studies (182 patients treated with [[methadone]] and 69 patients with [[clozapine]]) for CYP3A activity found that CYP3A SNPs themselves did not predict particularly well inter-individual variability in overall CYP3A activity. However, [[rs1057868]](T;T) individuals had a 1.6x increased CYP3A activity compared to [[rs1057868]](C) carriers (n=182, p=0.004), and the finding was replicated in a second independent dataset. The authors conclude that this [[POR]] gene SNP is a better predictor of overall CYP3A activity than CYP3A SNPs.{{PMID|19801957}}

{{PharmGKB
|RSID=rs1057868
|Name_s=
|Gene_s=
|Feature=
|Evidence=PubMed ID:19801957
|Annotation=Risk or phenotype-associated allele: T. Phenotype: POR*28 TT genotype presents a 1.6-fold increase in CYP3A activity compared with POR*28C carriers. Study size: 251. Study population/ethnicity: Caucasian patients from two independent studies (182 patients treated with methadone and 69 patients with clozapine). Significance metric(s): (n = 182, P = 0.004); (n = 69, P = 0.04) . Type of association: GN.
|Drugs=
|Drug Classes=
|Diseases=
|Curation Level=Curated
|PharmGKB Accession ID=PA165109204
}}

{{PMID Auto
|PMID=21770725
|Title=The P450 oxidoreductase *28 SNP is associated with low initial tacrolimus exposure and increased dose requirements in CYP3A5-expressing renal recipients
}}
{{PMID Auto
|PMID=17827787
|Title=Novel SNPs in cytochrome P450 oxidoreductase.
}}

{{PMID Auto
|PMID=18230729
|Title=Genetics of P450 oxidoreductase: sequence variation in 842 individuals of four ethnicities and activities of 15 missense mutations.
|OA=1
}}

{{PMID Auto
|PMID=22246422
|Title=Influence of cytochrome P450 oxidoreductase genetic polymorphisms on CYP1A2 activity and inducibility by smoking.
}}

{{GET Evidence
|gene=POR
|aa_change=Ala503Val
|aa_change_short=A503V
|impact=pharmacogenetic
|qualified_impact=Insufficiently evaluated pharmacogenetic
|inheritance=unknown
|quality_scores=Array
|dbsnp_id=rs1057868
|overall_frequency_n=2376
|overall_frequency_d=10156
|overall_frequency=0.23395
|n_genomes=18
|n_genomes_annotated=0
|n_haplomes=24
|n_articles=1
|n_articles_annotated=1
|gene_in_genetests=Y
|in_pharmgkb=Y
|genetests_testable=Y
|genetests_reviewed=Y
|nblosum100=2
|autoscore=4
|webscore=N
|n_web_uneval=10
}}

{{PMID Auto
|PMID=24113216
|Title=Single-nucleotide polymorphisms in P450 oxidoreductase and peroxisome proliferator-activated receptor-α are associated with the development of new-onset diabetes after transplantation in kidney transplant recipients treated with tacrolimus
}}

{{PMID Auto
|PMID=24921414
|Title=Impact of PPARA and POR polymorphisms on tacrolimus pharmacokinetics and new-onset diabetes in kidney transplant recipients
}}
{{on chip | 23andMe v3}}
{{on chip | 23andMe v4}}