ALDH2 rs2302761: Alcohol Metabolism and Flushing Trait
The rs2302761 variant is a single-nucleotide polymorphism located in the ALDH2 gene region. It is in linkage disequilibrium with key loci in the ALDH2 genomic cluster and is statistically associated with variations in alcohol metabolic rates and physiological alcohol flushing. Evidence for its direct functional impact remains limited, as it frequently tags broader regional haplotypes.
What each genotype means
Normal enzyme activity
This genotype is associated with fully functional ALDH2 enzyme activity, which efficiently converts acetaldehyde into acetate during alcohol metabolism. Individuals with this genotype typically do not experience the alcohol-induced flushing response linked to ALDH2 deficiency.
This is the most common genotype globally, though it is less frequent in East Asian populations where the variant allele is more prevalent.
Reduced enzyme activity
This genotype, often referred to in literature as ALDH2*1/*2, results in reduced ALDH2 enzyme activity and slower clearance of acetaldehyde. Carriers may experience facial flushing, nausea, or tachycardia after alcohol consumption, which is a trait often associated with a lower risk of alcohol dependence.
This genotype is common in East Asian populations, where approximately 35-45% of individuals may carry at least one copy of the inactive variant.
Inactive enzyme activity
This genotype, often referred to as ALDH2*2/*2, results in a near-total loss of ALDH2 enzyme function, leading to a significant accumulation of acetaldehyde after alcohol intake. Individuals with this genotype are highly likely to experience severe flushing and physical discomfort when consuming alcohol, which serves as a strong protective factor against heavy alcohol consumption.
This genotype is found primarily in East Asian populations and is rare in individuals of European or African ancestry.
Genomic Location and the ALDH2 Gene
The single-nucleotide polymorphism rs2302761 is positioned within the aldehyde dehydrogenase 2 (ALDH2) genomic locus on human chromosome 12. The ALDH2 gene encodes a vital mitochondrial enzyme responsible for the second step of alcohol metabolism: the conversion of acetaldehyde, a toxic intermediate formed when alcohol is processed, into harmless acetate. Acetaldehyde is a cellular toxin and reactive molecule capable of damaging DNA and causing tissue irritation. When ALDH2 function is altered or reduced, acetaldehyde accumulates in the bloodstream after drinking alcohol, leading to physiological symptoms such as facial flushing, accelerated heart rate, nausea, and headache. While the functional missense mutation rs671 (ALDH2*2) is the classical driver of severe enzymatic deficiency, neighboring variants like rs2302761 reside in non-coding or linked regions within the wider ALDH2 haplotype block, reflecting subtle genomic diversity in this metabolic locus.
Linkage Disequilibrium and Scientific Evidence
Scientific evidence surrounding rs2302761 indicates that it acts primarily as a marker in linkage disequilibrium with other variants across the ALDH2 gene. Rather than directly crippling the enzyme on its own, alleles at rs2302761 are often co-inherited with functional alleles that modulate alcohol metabolic rate and the intensity of the alcohol-induced flushing reaction. In genetic association studies, rs2302761 has been investigated alongside other common polymorphisms to track regional haplotype patterns. Current evidence grading for rs2302761 is categorized as limited because its independent, isolated contribution to enzymatic activity is secondary to major structural variants in the gene. Association studies demonstrate correlated statistical signals with subjective and physiological reactions to alcohol, but isolating its distinct biological mechanism from surrounding variation remains challenging.
Ancestry and Population Distribution
The distribution of rs2302761 varies substantially depending on ancestral background. Population genetics data indicate that the minor allele frequency (MAF) ranges between approximately 0.15 and 0.25 across East Asian cohorts, mirroring the regional prevalence of ALDH2 variation in these communities. By contrast, the minor allele is rare or virtually absent in populations of European and African ancestry, where the surrounding haplotype structure differs significantly. These geographic and ancestral disparities reflect evolutionary pressures and population history in East Asia, where genetic variations in alcohol-metabolizing enzymes first expanded thousands of years ago. Because frequency profiles are markedly population-specific, interpretations of rs2302761 must always be considered within an individual's specific ancestral context.
What You Can and Cannot Do With This Information
Understanding your rs2302761 genotype offers educational insight into your genetic heritage and how your body may process alcohol metabolites, but it is not a medical diagnosis. Genetic association at this locus does not predict personal health outcomes with absolute certainty, as lifestyle factors, overall diet, and other genes (such as ADH1B) strongly shape alcohol processing. This genetic result cannot be used to determine an individual's blood alcohol concentration, legal fitness to drive, or definitive tolerance thresholds. Furthermore, while ALDH2 activity plays a role in activating certain cardiovascular medications like nitroglycerin, variants at linked markers like rs2302761 do not substitute for formal clinical testing. Readers taking cardiovascular drugs or experiencing pronounced flushing, lightheadedness, or discomfort should consult a qualified physician or pharmacist before altering any medical care or habits.
How common is this variant?
The minor allele frequency for rs2302761 is approximately 0.15 to 0.25 across East Asian populations, while remaining rare or virtually absent among European and African groups.
Frequently asked questions
What is rs2302761 and how does it relate to alcohol flushing?
The rs2302761 variant is a genetic single-nucleotide polymorphism located within the ALDH2 gene cluster. It is statistically correlated with alcohol metabolism and facial flushing traits, often because it is co-inherited with functional genetic changes that slow the breakdown of acetaldehyde.
Does having the rs2302761 variant cause alcohol intolerance?
Not directly on its own. While rs2302761 is linked to altered metabolic rates, noticeable alcohol intolerance or flushing syndrome is primarily driven by functional missense variants in the ALDH2 locus, particularly rs671.
How common is rs2302761 across different ancestries?
This variant shows clear ancestral patterns: its minor allele frequency is around 15% to 25% in East Asian populations, but it is rarely found in people of European or African descent.
Can rs2302761 inform my response to heart medications?
While ALDH2 enzymes participate in bioactivating medications such as sublingual nitroglycerin, markers like rs2302761 only provide research-grade association data. Any questions about cardiovascular medication efficacy or dosing should be discussed directly with your clinician or pharmacist.
Sources & further reading
Educational information only, last refreshed 9/6/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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The ALDH2*2 Glu504Lys dominant-negative substitution impairs toxic acetaldehyde clearance during ethanol metabolism, increases alcohol-induced facial flushing, and diminishes hemodynamic responsiveness to sublingual nitroglycerin.
Regulatory upstream polymorphism in linkage disequilibrium with the classic ALDH2*2 allele modulating alcohol-induced facial flushing and peak acetaldehyde accumulation.