Alcohol Flush

Your result, the one DNA position behind it, and what the research says.

8/10 confidence.

About Alcohol Flush

Your body breaks alcohol down in two steps: first into acetaldehyde, then into harmless acetate. ALDH2 runs the second step. This variant swaps one building block of the enzyme and cripples it, so acetaldehyde builds up instead of being cleared. Acetaldehyde is what produces the flushing, the warmth, the racing heart and the queasiness. The effect is unusually strong for a single common variant, and it is one of the clearest examples of a visible reaction traced to one position in the genome.

Good to know: Flushing is caused by acetaldehyde building up, not by alcohol itself. One faulty copy is enough because the broken subunits disrupt the working ones. This variant is common in East Asian ancestry and very rare elsewhere.

Fun fact: This is the same compound that disulfiram medication deliberately causes to accumulate; the variant produces a similar reaction naturally.

Discovery: The inactive form of the enzyme was identified in the early 1980s while researchers were investigating why alcohol flushing was so common in East Asia.

The Variant

The single variant behind this trait

Gene: ALDH2

Variant (rsID): rs671

Location: Chr 12:111,803,962

dbSNP rs671

The studies

Uncovering newly identified aldehyde dehydrogenase 2 genetic variants that lead to acetaldehyde accumulation after an alcohol challenge (Rwere F et al., Journal of translational medicine, 2024)

Sex- and ALDH2-dependent differences in alcohol metabolism and psychomotor performance: a study in Han Chinese adults after binge drinking (Ye Y et al., Annals of medicine, 2025)

Other lifestyle traits

Caffeine Clearance: Two positions in the regulatory DNA of CYP1A2, the liver enzyme that breaks down about 95 percent of your caffeine, setting how fast it leaves your system.

Caffeine Jitters: A variant in the brain receptor caffeine actually acts on, linked to how jittery or wired a moderate dose leaves you feeling.

Odor After Certain Foods: A variant in a liver enzyme that clears a fishy-smelling compound produced when gut bacteria digest choline-rich foods like eggs, fish and beans.

Back to All Traits

Content updated September 2026.

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