Alternative Names
Asian Flush; Asian Blush
Symptoms & Characteristics
Alcohol (or ethanol) is poisonous to the human body. One of the functions of the liver is to break down alcohol into substances that the body can use or otherwise excrete in urine. This breakdown (or metabolism) of alcohol requires multiple steps and different enzymes.
- An enzyme called alcohol dehydrogenase (ADH) converts alcohol to acetaldehyde. Unfortunately, acetaldehyde is even more harmful to the body than ethanol. Acetaldehyde poisoning is the major cause of "hangovers."
- An enzyme called aldehyde dehydrogenase-2 (ALDH2) then breaks down acetaldehyde into vinegar (or acetic acid), which is excreted in urine or is used to build fat.
- A final enzyme breaks down acetic acid into carbon dioxide and water. Other enzymes may also contribute to alcohol metabolism with chronic heavy drinking.
Defects in any of these important enzymes can disrupt the process of alcohol metabolism resulting in unpleasant symptoms, like drowsiness, increased heart rate, nausea, facial flushing, and the symptoms of reduced blood pressure. Some people even experience these unpleasant symptoms after only a small amount of alcohol. This adverse reaction to alcohol is called alcohol flush reaction.
Management & Treatment
Treatment options for alcohol flush reaction may include avoidance of alcohol and medications to reduce symptoms.
How Common Is It?
Alcohol flush reaction is most common in people of Asian descent and is sometimes referred to as "Asian Flush."
Genetics & Inheritance
Mutations in genes responsible for the production of the different enzymes in the alcohol metabolism pathway can lead to alcohol flush reaction. However, the main genetic cause of alcohol flush reaction is a genetic variant of the ALDH2 gene called ALDH2*2. This variant affects the production of a functional ALDH2 enzyme. As such, acetaldehyde cannot be effectively broken down into vinegar and builds up in the body. Having either one or two copies of the ALDH2*2 genetic variant causes alcohol flush reaction.
Genetic Testing
Informational genetic testing for the ALDH2*2 genetic variant associated with alcohol flush reaction is available online (over the internet) as part of a whole genome scan. Whole genome scanning involves analyzing thousands of SNPs at once related to a number of different health conditions.
- At this point, many genetic professionals do not consider this testing clinically useful or medically relevant, but for informational purposes only. Go to the Tests tab to link to the best providers, compare providers and read provider reviews.
For more information on the genetics of alcohol flush reaction, the benefits and limitations of genetic testing, accurate diagnosis, and recurrence risk; if may be helpful to speak with a genetic counselor.
- A board-certified genetic counselor is available by telephone.
Support & More Information
More information can be found at:
Sources