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Around 30–50% of East Asians carry the [[mitochondria]]l rs671 (ALDH2*2) allele, which results in a less functional [[acetaldehyde dehydrogenase]] enzyme, responsible for the breakdown of acetaldehyde, and accounts for most incidents of alcohol flush reaction worldwide. According to the analysis by [[HapMap]] project, 30% to 50% of people of Chinese, Japanese, and Korean ancestry have at least one ''ALDH2*2'' allele, while it is rare among Europeans and Sub-Saharan Africans.<ref name=":2">{{cite web|url=http://www.snpedia.com/index.php/Rs671|title=Rs671}}</ref> |
Around 30–50% of East Asians carry the [[mitochondria]]l rs671 (ALDH2*2) allele, which results in a less functional [[acetaldehyde dehydrogenase]] enzyme, responsible for the breakdown of acetaldehyde, and accounts for most incidents of alcohol flush reaction worldwide. According to the analysis by [[HapMap]] project, 30% to 50% of people of Chinese, Japanese, and Korean ancestry have at least one ''ALDH2*2'' allele, while it is rare among Europeans and Sub-Saharan Africans.<ref name=":2">{{cite web|url=http://www.snpedia.com/index.php/Rs671|title=Rs671}}</ref> |
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The rs671 allele is native to [[East Asia]] and most common in southeastern |
The rs671 allele is native to [[East Asia]] and most common in southeastern China. Analysis correlates the rise and spread of rice cultivation in [[South China]] with the spread of the allele.<ref name=Yi2010/> The reasons for this positive selection are not known, but it has been hypothesized that elevated concentrations of acetaldehyde may have conferred protection against certain parasitic infections, such as ''[[Entamoeba histolytica]]''.<ref>{{cite journal|author =Oota|title=The evolution and population genetics of the ALDH2 locus: random genetic drift, selection, and low levels of recombination|year=2004|journal=[[Annals of Human Genetics]]|volume=68|issue=2|pages=93–109|display-authors=etal|doi=10.1046/j.1529-8817.2003.00060.x|pmid=15008789}}</ref> |
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Additionally, in around 80% of [[East Asian people|East Asians]], the rapid accumulation of acetaldehyde is worsened by another gene variant; in this case the allele ''[[ADH1B|ADH1B*2]],'' which results in the [[alcohol dehydrogenase]] [[enzyme]] converting alcohol to toxic [[acetaldehyde]] more quickly than other gene variants common outside of [[East Asia]].<ref name=Yi2010/><ref name="Eng et al.">{{cite journal|vauthors=Eng MY, Luczak SE, Wall TL|date=2007|title=ALDH2, ADH1B, and ADH1C genotypes in Asians: a literature review|journal=Alcohol Research & Health|volume=30|issue=1|pages=22–27|pmc=3860439|pmid=17718397}}</ref> |
Additionally, in around 80% of [[East Asian people|East Asians]], the rapid accumulation of acetaldehyde is worsened by another gene variant; in this case the allele ''[[ADH1B|ADH1B*2]],'' which results in the [[alcohol dehydrogenase]] [[enzyme]] converting alcohol to toxic [[acetaldehyde]] more quickly than other gene variants common outside of [[East Asia]].<ref name=Yi2010/><ref name="Eng et al.">{{cite journal|vauthors=Eng MY, Luczak SE, Wall TL|date=2007|title=ALDH2, ADH1B, and ADH1C genotypes in Asians: a literature review|journal=Alcohol Research & Health|volume=30|issue=1|pages=22–27|pmc=3860439|pmid=17718397}}</ref> |
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| Alcohol flush reaction | |
|---|---|
| Other names | Asian flush syndrome, Asian flush reaction, Asian glow, Asian red face glow |
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| Facial flushing. Before (left) and after (right) drinking alcohol. A 22-year-old East Asian man who is ALDH2 heterozygote showing the reaction.[1] | |
| Specialty | Toxicology |
| Frequency | 36% of East Asians[2][1][3] |
Alcohol flush reaction is a condition in which a person develops flushes or blotches associated with erythema on the face, neck, shoulders, and in some cases, the entire body after consuming alcoholic beverages. The reaction is the result of an accumulation of acetaldehyde, a metabolic byproduct of the catabolic metabolism of alcohol, and is caused by an aldehyde dehydrogenase 2 deficiency.[4]
This syndrome has been associated with lower than average rates of alcoholism, possibly due to its association with adverse effects after drinking alcohol.[5] However, it has also been associated with an increased risk of esophageal cancer in those who do drink.[1][6][7]
Heat flush is common in Indigenous peoples of the Americas, East Asians, with approximately 30 to 50% of Chinese, Japanese, and Koreans showing characteristic physiological responses to drinking alcohol that includes facial flushing, nausea, headaches and a fast heart rate.[1][2][3][8]
Individuals who experience the alcohol flushing reaction may be less prone to alcoholism. Disulfiram, a drug sometimes given as treatment for alcoholism, works by inhibiting acetaldehyde dehydrogenase, causing a five to tenfold increase in the concentration of acetaldehyde in the body. The resulting irritating flushing reaction tends to discourage affected individuals from drinking.[9][10]
The most obvious symptom is flushing on a person's face and body after drinking alcohol.[4] Other effects include "nausea, headache and general physical discomfort".[11]
Many cases of alcohol-induced respiratory reactions, which involve rhinitis and worsening of asthma, develop within 1–60 minutes of drinking alcohol and are due to the same causes as flush reactions.[12]
![{\displaystyle {\ce {H}}{-}{\overset {\displaystyle {\ce {H}} \atop |}{\underset {| \atop \displaystyle {\ce {H}}}{\ce {C}}}}{-}{\overset {\displaystyle {\ce {H}} \atop |}{\underset {| \atop \displaystyle {\ce {H}}}{\ce {C}}}}{\ce {-O-H->[{\ce {ADH}}]H}}{-}{\overset {\displaystyle {\ce {H}} \atop |}{\underset {| \atop \displaystyle {\ce {H}}}{\ce {C}}}}{-}{\overset {\displaystyle {\ce {H}} \atop |}{\underset {\| \atop \displaystyle {\ce {O}}}{\ce {C}}}}{\ce {->[{\ce {ALDH}}]H}}{-}{\overset {\displaystyle {\ce {H}} \atop |}{\underset {| \atop \displaystyle {\ce {H}}}{\ce {C}}}}{-}{\overset {\color {white}{\displaystyle {\ce {H}} \atop |}}{\underset {\| \atop \displaystyle {\ce {O}}}{\ce {C}}}}{\ce {-O-H}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/8e29ab9d559420e2df0bf9ff99bef27374c71271)
Alcohol flush reaction is best known as a condition that is experienced by people of East Asian descent; due to this, the condition is often given names such as "Asian flush" or "Asian glow."
Around 30–50% of East Asians carry the mitochondrial rs671 (ALDH2*2) allele, which results in a less functional acetaldehyde dehydrogenase enzyme, responsible for the breakdown of acetaldehyde, and accounts for most incidents of alcohol flush reaction worldwide. According to the analysis by HapMap project, 30% to 50% of people of Chinese, Japanese, and Korean ancestry have at least one ALDH2*2 allele, while it is rare among Europeans and Sub-Saharan Africans.[8]
The rs671 allele is native to East Asia and most common in southeastern China. Analysis correlates the rise and spread of rice cultivation in South China with the spread of the allele.[5] The reasons for this positive selection are not known, but it has been hypothesized that elevated concentrations of acetaldehyde may have conferred protection against certain parasitic infections, such as Entamoeba histolytica.[13]
Additionally, in around 80% of East Asians, the rapid accumulation of acetaldehyde is worsened by another gene variant; in this case the allele ADH1B*2, which results in the alcohol dehydrogenase enzyme converting alcohol to toxic acetaldehyde more quickly than other gene variants common outside of East Asia.[5][14]
Those with facial flushing due to ALDH2 deficiency may be homozygotes, with two alleles of low activity, or heterozygotes, with one low-activity and one normal allele. Homozygotes for the trait find consumption of large amounts of alcohol to be so unpleasant that they are generally protected from esophageal cancer, but heterozygotes are able to continue drinking. However, an ALDH2-deficient drinker has four to eight times the risk of developing esophageal cancer as a drinker not deficient in the enzyme.[1][7]
Because most East Asians have a variant in the ADH gene, this risk is lowered somewhat because the ADH variant reduces the risk of esophageal cancer four-fold. However, ALDH2-deficient people who do not carry this ADH variant are at the highest risk of cancer as these risk factors act in a multiplicative manner through increasing exposure time to salivary acetaldehyde.[7]
The idea that acetaldehyde is the cause of the flush is also shown by the clinical use of disulfiram (Antabuse), which blocks the removal of acetaldehyde from the body via ALDH inhibition. The high acetaldehyde concentrations described share similarity to symptoms of the flush (flushing of the skin, accelerated heart rate, shortness of breath, throbbing headache, mental confusion and blurred vision).[15]
For measuring the level of flush reaction to alcohol, the most accurate method is to determine the level of acetaldehyde in the blood stream. This can be measured through both a breathalyzer test or a blood test.[16] Additionally, measuring the amount of alcohol metabolizing enzymes alcohol dehydrogenases and aldehyde dehydrogenase through genetic testing can predict the amount of reaction that one would have.
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{{cite web}}: CS1 maint: archived copy as title (link)
| Classification |
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| General |
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| Combined substance use |
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| Alcohol |
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| Caffeine |
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| Cannabis |
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| Cocaine |
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| Hallucinogen |
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| Nicotine |
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| Opioids |
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| Sedative / hypnotic |
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| Stimulants |
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| Volatile solvent |
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| Related |
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Diseases of the human digestive system
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| Upper GI tract |
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| Lower GI tract Enteropathy |
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| GI bleeding |
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| Accessory |
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| Other |
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