What you carry at this position in your DNA and what research says about it.
Medication Clearance: 6/10 evidence, 47 publications.
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Sample genotype (not yours): C/C
Typical Medication Clearance and Baseline Lipid Levels
Standard enzyme activity levels support typical processing speeds for many common medications. Lipid levels and kidney function markers generally remain at baseline.
What this genotype means: Standard drug clearance rates; Baseline lipid levels; Typical kidney filtration markers.
Sample genotype (not yours): C/T
Slightly Faster Medication Clearance and Minor Lipid Shifts
A single copy of the variant slightly accelerates the clearance of certain medications. This can also lead to minor increases in triglyceride levels and subtle improvements in kidney markers.
What this genotype means: Slightly accelerated drug metabolism; Minor lipid elevations; Subtle kidney filtration improvements.
Sample genotype (not yours): T/T
Fast Medication Clearance and Elevated Lipid Levels
Two copies of the variant significantly accelerate the clearance of many common medications. This profile is also linked to higher triglyceride levels alongside markers of better kidney function.
What this genotype means: Rapid clearance of CYP3A-metabolized medications; Elevated triglycerides and cholesterol; Improved kidney function markers.
Gene function and biological role
Gene Function: The POR gene encodes cytochrome P450 oxidoreductase, a vital helper protein in the endoplasmic reticulum [1]. It serves as the exclusive electron donor for all microsomal cytochrome P450 enzymes, which are responsible for metabolizing the vast majority of clinical drugs and synthesizing key hormones [1] [2]. Without functional POR, these critical enzymes cannot perform oxidation reactions [2]. Variations in this gene can significantly alter how efficiently electrons are transferred, thereby influencing the clearance rates of numerous medications [3]. It also plays a role in steroid hormone synthesis and lipid metabolism [1] [2].
Variant Impact: This missense variant, known as p.Ala500Val or POR*28, alters a single amino acid in the cytochrome P450 oxidoreductase protein [1]. This specific change from alanine to valine affects the electron-binding region of the enzyme [1]. While some laboratory studies suggested this alteration might decrease enzyme activity, clinical evidence consistently shows it enhances the metabolism of several medications [1] [4]. It is particularly influential in driving the activity of the CYP3A enzyme family, which processes over half of all prescribed drugs [3]. The variant is highly common across global populations, with carrier rates exceeding thirty percent in many ancestries [1].
Key Insight: This single helper gene variant acts as a master dial for over half of all common medications, often predicting drug clearance rates better than variations in the primary metabolizing enzymes themselves.
Location: POR. Chromosome 7 · 7q11.23 · 76.0 Mb
Estimated prevalence by population
Global 53.4%; European 51.0%; African 66.6%; East Asian 38.2%; South Asian 41.4%; Americas 50.0%; Ashkenazi 55.2%; Finnish 34.4%; Middle Eastern 60.1%; Amish 43.0%.
Estimated CC genotype frequency.
Global 38.8%; European 40.8%; African 30.0%; East Asian 47.2%; South Asian 45.9%; Americas 41.4%; Ashkenazi 38.2%; Finnish 48.5%; Middle Eastern 34.8%; Amish 45.2%.
Estimated CT genotype frequency.
Global 7.9%; European 8.2%; African 3.4%; East Asian 14.6%; South Asian 12.7%; Americas 8.6%; Ashkenazi 6.6%; Finnish 17.1%; Middle Eastern 5.0%; Amish 11.9%.
Estimated TT genotype frequency.
Showing effects for C/C genotype
Pharmacogenomics
Drug Metabolism Enzyme Activity
Medication Clearance. Evidence: 6/10. Source: PMID 19801957. Typical.
Cardiovascular & Metabolic
Lipids & Cholesterol
Triglycerides. Evidence: 9/10. Source: PMID 34887591. Typical.
Cholesterol Levels. Evidence: 9/10. Source: PMID 34887591. Typical.
Organ Systems
Kidney Function & Disease
Kidney Function. Evidence: 9/10. Source: PMID 39927731. Typical.
Neurology & Mental Health
Behavioral & Personality Traits
Coffee Consumption. Evidence: 9/10. Source: PMID 31046077. Typical.
Showing effects for C/T genotype
Medication Clearance. Evidence: 6/10. Source: PMID 19801957. Slightly Faster.
Triglycerides. Evidence: 9/10. Source: PMID 34887591. Slightly Elevated.
Cholesterol Levels. Evidence: 9/10. Source: PMID 34887591. Slightly Elevated.
Kidney Function. Evidence: 9/10. Source: PMID 39927731. Slightly Better.
Coffee Consumption. Evidence: 9/10. Source: PMID 31046077. Slightly Higher.
Showing effects for T/T genotype
Medication Clearance. Evidence: 6/10. Source: PMID 19801957. 1.6x Faster.
Triglycerides. Evidence: 9/10. Source: PMID 34887591. Elevated.
Cholesterol Levels. Evidence: 9/10. Source: PMID 34887591. Elevated.
Kidney Function. Evidence: 9/10. Source: PMID 39927731. Better.
Coffee Consumption. Evidence: 9/10. Source: PMID 31046077. Higher.
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
Standard enzyme activity levels support typical processing speeds for many common medications [1]. Individuals with this baseline profile tend to metabolize drugs like tacrolimus, clozapine, and methadone at a standard rate, avoiding the rapid clearance that can make dosing difficult [1] [2]. Lipid profiles, including triglycerides and cholesterol, typically remain at baseline levels [3]. Kidney function markers, such as creatinine and glomerular filtration rate, also show standard patterns [4]. This common genetic profile represents the standard reference point for drug dosing guidelines.
Standard drug clearance rates; Baseline lipid levels; Typical kidney filtration markers.
Sample genotype: CT (Heterozygous)
Carrying a single copy of the variant slightly accelerates the clearance of certain medications [1]. This intermediate enzyme activity can lead to slightly faster processing of drugs like tacrolimus, which may occasionally lower its blood levels [1] [2]. Triglyceride and cholesterol levels may show very minor elevations compared to the baseline [3]. Conversely, kidney function markers like creatinine may be slightly lower, suggesting a subtle positive effect on filtration efficiency [4]. Caffeine is also processed slightly faster, which can subtly influence daily coffee consumption habits [5].
Slightly accelerated drug metabolism; Minor lipid elevations; Subtle kidney filtration improvements.
Sample genotype: TT (Homozygous)
Two copies of the variant significantly accelerate the clearance of many common medications [1]. This profile is associated with a 1.6-fold increase in overall CYP3A enzyme activity, leading to rapid processing of drugs like tacrolimus, clozapine, and methadone [1] [2]. Because these medications are cleared so quickly, standard doses may sometimes prove less effective [2]. Additionally, this genetic setup is linked to higher levels of triglycerides and LDL cholesterol [3]. On the positive side, kidney function markers are often improved, characterized by lower creatinine and higher glomerular filtration rates [4]. There is also a tendency toward higher caffeine consumption due to faster caffeine clearance [5].
Rapid clearance of CYP3A-metabolized medications; Elevated triglycerides and cholesterol; Improved kidney function markers.
Variants with shared genetic architecture
rs17685 · POR Gene · Chr 7 · Caffeine Metabolism
rs41301394 · POR Gene · Chr 7 · Kidney Function
rs2302429 · POR Gene · Chr 7 · Cholesterol Levels
Pharmacogenomics of human P450 oxidoreductase.
The power of genetic diversity in genome-wide association studies of lipids.
A genome-wide association study of bitter and sweet beverage consumption.
Content updated August 2026.
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