Alcohol flush and ALDH2
The ALDH2*2 variant (rs671) slows the breakdown of acetaldehyde, causes facial flushing after alcohol and raises cancer risk for people who drink anyway.
The short answer
The ALDH2*2 variant (rs671) cripples the enzyme that clears acetaldehyde, the toxic first breakdown product of alcohol. Carriers flush, feel their heart race and often feel sick after small amounts. About 540 million people carry it, roughly 8% of the world, mostly of East Asian descent. Carriers who keep drinking face a higher risk of cancers of the esophagus and the head and neck.
What the variant does
Alcohol is broken down in two steps. The first produces acetaldehyde; ALDH2 handles the second, turning acetaldehyde into harmless acetate. The rs671 variant swaps one amino acid (E504K) and leaves the enzyme with a fraction of its normal activity, so acetaldehyde builds up in the blood. Flushing, palpitations, headache and nausea follow.1
Why the flush matters
Acetaldehyde damages DNA. A review in Disease Models & Mechanisms notes that East Asian carriers of ALDH2*2 who drink regularly have a higher risk of esophageal, head and neck cancers than non-carriers, and that in the China Kadoorie Biobank, carriers who drank despite the flush showed a dose-dependent rise in alcohol-related cancers.1 Researchers at the US National Institute on Alcohol Abuse and Alcoholism argued in 2009 that the flush itself should be treated as a warning sign for this risk.2
| Your result at rs671 | What it means |
|---|---|
| GG | Typical ALDH2 activity. |
| GA | One copy of ALDH2*2. Reduced activity; flushing is common. |
| AA | Two copies. Very low activity; most people cannot tolerate alcohol at all. |
What GenomEats suggests
- Treat the flush as information about risk. Working around it with tolerance or tricks leaves the risk in place.
- The less you drink, the better. Tolerance that builds over time does not make acetaldehyde less harmful.
- Smoking and drinking together compound the risk for upper digestive tract cancers.
Sources
- Chen CH, Kraemer BR, Mochly-Rosen D. ALDH2 variance in disease and populations. Dis Model Mech. 2022;15(6):dmm049601. pmc.ncbi.nlm.nih.gov
- Brooks PJ, Enoch MA, Goldman D, Li TK, Yokoyama A. The alcohol flushing response: an unrecognized risk factor for esophageal cancer from alcohol consumption. PLoS Med. 2009;6(3):e50. doi.org
This page is educational and does not diagnose or treat any condition. Talk to a qualified clinician before making medical decisions based on a genetic result.