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Aldehyde Dehydrogenase Genetics

Alcohol Flush Reaction is the Simplest Way to Know if You Have ALDH2 Deficiency

Typically, an individual will know if they have ALDH2 Deficiency if they experience redness of the face and skin when drinking alcohol. This response is called Alcohol Flush Reaction, or often called 'Asian Flush' or 'Asian Glow'. This negative reaction is a result of a toxic compound called acetaldehyde building up to very high levels when drinking. When we drink, we break down alcohol into acetaldehyde. Those with ALDH2 Deficiency are unable to breakdown acetaldehyde properly because of a mutated ALDH2 Enzyme, and so it accumulates, causing the symptoms of Alcohol Flush Reaction and other damage.

In addition to facial redness, Alcohol Flush Reaction often comes with other symptoms, including increased heart rate, overheating, itchiness, a stuffy nose, nausea, headache, and intensified hangover symptoms. To learn more about Alcohol Flush Reaction, visit What's Alcohol Flush Reaction?

What if my face only turns red when I drink certain kinds of alcohol?

Since Alcohol Flush Reaction is cause by a build-up of acetaldehyde, which is a metabolite of alcohol, those with ALDH2 Deficiency will experience Alcohol Flush Reaction regardless of what type of alcohol they consume. If you turn red only when drinking a particular type of alcohol, say red wine for instance, this is likely a reaction to something in the wine rather than a reaction to the alcohol itself.  

How do I know if I have ALDH2 Deficiency if I don't drink alcohol?

For those who are not of drinking age, or do not drink, you may be able to know if you have ALDH2 Deficiency if your parents experience Alcohol Flush Reaction. ALDH2 Deficiency is caused by a genetic mutation that is passed from parents to their children. The ALDH2 genetic mutation is a dominant gene, meaning it is likely that parents will pass it on to their children.

Below are two scenarios demonstrating this inheritance process. For every gene, each person has 2 copies: one from their mother and one from their father. It only takes one mutated copy of the ALDH2 gene to cause ALDH2 Deficiency. Each parent randomly passes down one of their 2 genes to their child. If a parent has 1 mutated ALDH2 gene, there is a 50% chance his or her child will have ALDH2 Deficiency. If a parent has 2 mutated ALDH2 genes, there is a 100% chance his or her child will have ALDH2 Deficiency. The diagrams below help illustrate this.


The mother has ALDH2 Deficiency with 1 mutated ALDH2 Gene. The father has 2 normal ALDH2 Genes. At random, each child will get one of their mother’s genes. On average, 50% of the children will receive the mother’s mutated gene and will have ALDH2 Deficiency.


The father has ALDH2 Deficiency with 2 mutated genes. Since the children will get 1 gene from their mother and 1 from their father, each child will have 1 mutated gene and 1 normal gene. If a parent has 2 mutated ALDH2 genes, all of his or her children will have ALDH2 Deficiency. 

A simple genetics test can tell you whether or not you have ALDH2 Deficiency

A genetics test analyzes your DNA and can tell you what genes you have. There are a few at-home genetics tests that can tell you if you have a mutated ALDH2 gene, and if so, whether you have 1 mutated gene, or 2. They will mail you a kit in which you can provide a saliva sample, and then mail it back to be analyzed. You will then get a full report back that tells you not only about ALDH2 Deficiency, but about a wide variety of genes with helpful resources. One of these companies is 23andMe. The service costs $199 to be completed. 

For more detailed information about the Aldehyde Dehydrogenase 2 Enzyme, ALDH2 Deficiency, and the genetics behind the enzyme deficiency, go to

More questions about ALDH2 Deficiency and Essential AD2? Visit our Frequently Asked Questions.