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
Last Reviewed December 28, 2009