Alcohol response (flushing & dependence risk)

Your reaction to alcohol is shaped by two enzymes working in sequence. ADH1B turns alcohol into acetaldehyde (a toxic by-product), and ALDH2 clears that acetaldehyde away. A fast ADH1B makes acetaldehyde quickly, while a deficient ALDH2 clears it slowly, and both leave more acetaldehyde around, which causes flushing and tends to lower the risk of alcohol dependence. Because they act on the same chemical from different ends, they are read together.

Possible results

Typical alcohol response. You don't carry the ALDH2 deficiency allele or the fast ADH1B allele, so from what these two genes show you process alcohol at a typical pace without the strong flush-and-nausea reaction. This says nothing about how much you should drink, since tolerance, habit and overall health matter far more, and the usual sensible-drinking guidance still applies.

Fast metabolism, mild aversion. Your ALDH2 works normally, but you carry the fast ADH1B variant, so your body converts alcohol into acetaldehyde more quickly and that by-product can pile up briefly. Drinking may feel unpleasant sooner, with some flushing or queasiness, which is linked to a lower chance of heavy drinking or alcohol dependence. The effect is gentler than ALDH2 deficiency because your body still clears the acetaldehyde efficiently.

Moderate flush when drinking. You carry one copy of the ALDH2 deficiency variant, so the acetaldehyde-clearing enzyme works only partway and alcohol builds up faster than usual, giving the facial flushing, fast heartbeat and queasiness many people feel. The reaction is real but milder than with two copies, and a fast ADH1B (if you also carry it) makes it come on sooner. Drinking less is the simplest way to stay comfortable, and heavier drinking with this genotype still carries some raised cancer risk.

Strong flush, best to avoid alcohol. You carry two copies of the ALDH2 deficiency variant, so the enzyme that clears acetaldehyde (alcohol's toxic by-product) barely works and even small amounts of alcohol can cause intense flushing, a racing heart and nausea. Beyond the discomfort, regular drinking with this genotype is linked to a markedly higher risk of esophageal cancer, so many people with it avoid alcohol entirely. This is the strongest flush pattern, and your ADH1B variant (if any) only adds to it.

Evidence & sources

This panel reads ALDH2, ADH1B.

Reads the two largest-effect alcohol variants common in East Asia: the strong-flush ALDH2 variant and the fast-metabolism ADH1B variant. Together these are essentially the whole common-variant story for the flush response, though a few rarer alcohol-related variants are not tested.

Related

Adult lactose digestion · Beta-carotene to vitamin A conversion (BCO1) · Caffeine metabolism speed · Fat taste sensitivity (CD36) · Total cholesterol · Triglycerides · Vitamin D status (low-D genetic burden)