Looked up a few more papers. It seems (though maybe someone will find newer info that I missed) that the Asian and native American alcohol intolerance differs genetically. But since both alcohol tolerant and intolerant genotypes both exist in Asian populations, it could mean that native Americans derived from an alcohol tolerant group and the flushing reaction to alcohol is a de novo mutation.
J Stud Alcohol. 1999 Mar;60(2):149-58. Related Articles, Links
An examination of ALDH2 genotypes, alcohol metabolism and the flushing response in Native Americans.
Gill K, Eagle Elk M, Liu Y, Deitrich RA.
Alcohol Research Center, Department of Pharmacology, University of Colorado Health Sciences Center, Denver, USA.
OBJECTIVE: The study was designed to examine the relationship between aldehyde dehydrogenase (ALDH2) genotype and the flushing response in a population of Native Americans. METHOD: Objective measures of the flushing response were obtained by monitoring skin temperature, heart rate, blood pressure, as well as blood alcohol concentrations, in flushing and nonflushing Native Americans (n = 105) as well as in Oriental (n = 15) and white (n = 15) control subjects following a dose of alcohol (0.2 or 0.4 gm/kg). ALDH genotypes were determined via polymerase chain reaction followed by hybridization to 32P or biotin-labeled allele-specific oligonucleotide probes. RESULTS: There were no ALDH2 mutations detectable in Native Americans reporting the flushing response, nor any objective evidence of an Oriental-like response to alcohol. The rate of alcohol metabolism was shown to be the same among whites, Native flushers and Native nonflushers. CONCLUSIONS: The results demonstrate that the flushing reaction experienced by Native Americans appears to be milder and less unpleasant than the "Oriental" flushing reaction, with little effect on drinking frequency and amount. In addition, the flushing is not mediated by the ALDH2 mutation or elevated blood acetaldehyde. A critical analysis of the discrepancies in the literature regarding alcohol metabolism in Native Americans is provided.
Hum Hered. 1993 Mar-Apr;43(2):116-20. Related Articles, Links
Absence of the atypical mitochondrial aldehyde dehydrogenase (ALDH2) isozyme in Saskatchewan Cree Indians.
Dyck LE.
Department of Psychiatry, University of Saskatchewan, Saskatoon, Canada.
Three methods were employed to assess whether human volunteers (Caucasian, Asian or Cree Indian) possessed the typical or atypical mitochondrial aldehyde dehydrogenase (ALDH2) isozyme. These methods were: (1) questioning individuals about facial flushing responses following alcohol consumption; (2) application of the ethanol skin patch test, and (3) direct analysis using isoelectric focusing and activity staining of ALDH activity in hair root samples. The results from the three methods were in good agreement and revealed that only the typical ALDH2 isozyme was expressed in Saskatchewan Cree Indians. In agreement with previous reports, the typical ALDH2 was expressed in the Caucasian group of subjects, while both the typical and atypical forms were expressed in the Asian subjects.
Behav Genet. 1995 Jan;25(1):59-65. Related Articles, Links
Alcohol consumption by orientals in North America is predicted largely by a single gene.
Tu GC, Israel Y.
Primary Mechanisms Department, University of Toronto, Canada.
Orientals consume significantly less alcohol, and show a lower prevalence of alcohol abuse and dependence, than Caucasians. Sociological theories propose that this difference is due mainly to cultural factors. Physiological theories have suggested that the flushing reaction experienced by some Orientals serves as a deterrent to ethanol consumption. The flushing reaction is observed mainly in individuals who possess a mutation in the high-affinity aldehyde dehydrogenase (ALDH2) which renders the enzyme inactive. However, the tendency to flush correlates poorly with alcohol consumption, thus casting doubt on the physiological interpretations. The present study investigates the influence of the ALDH2 allele and of acculturation in North America on alcohol consumption by Orientals born in Canada or the United States. Oriental males carrying the inactive ALDH2(-) allele drink two-thirds less alcohol (6.1 +/- 1.5 vs. 18.2 +/- 2.8 drinks/4 weeks; p < 0.001), show one-third the prevalence of binge drinking (15.2 vs. 42.2%; p < 0.01), and are three times more likely to be abstainers (39.4 vs. 13.3%; p < 0.01) than Oriental ALDH2(+) males carrying the gene for the active enzyme. There were no significant differences in binge drinking or abstinence rates between ALDH2(+) Orientals and Caucasian males. Acculturation in North American society accounted for only 7-11% of the variance in overall consumption (p < 0.02). It is concluded that a single mutation in the high-affinity aldehyde dehydrogenase (ALDH2) gene predicts two-thirds of the alcohol consumption and excessive alcohol use by Oriental males born in North America.
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