theyeti

Hello phaedrus! Do realize that this study is about the carcinogenesis of acetaldehyde (from what the title indicates), and not about whether or not this mutation cause ethanol aversion. The authors already recognize the evidence that there is a variant that causes some Asians to not be able to digest alcohol. (Actually, they can't digest acetaldehyde, which is what's produced when an alcohol dehydrogenase enzyme acts on the ethanol. The acetaldehyde is actually what gets you intoxicated, and it's much more toxic than ethanol. The aldehyde dehydrogenase in question here converts acetaldedyde into acedic acid, which is the same thing as vinegar. Interesting aside: the same enzymes will convert methanol into formaldehyde , and then formaldehyde into formic acid respectively. Since formaldehyde is much more toxic than methanol, a person with methanol poisoning will actually be given an ethanol drip. This ties up the alcohol dehydrogenase and keeps it from coverting the methanol into formaldehyde. Pretty ironic, huh? )

Notice that the study you cite is 2000, whereas the one that I cited about discovering the mutation was from 1997. So the part about the mutation is not really germane; I'm sure the authors of the 2000 study referrenced the 1997 paper, but unfortuanately I can't get it online. (A search for "asians" didn't turn up anything, but either way I can't access full text). You are very much right in questioning whether or not 20 individuals is a proper sample size. But for the purposes of figuring out how many individuals have this variant, it's more or less irrelevant. The prevalence of this allele was determined long before by using epidemiological studies.

If you search the Alcoholism journal site for ALDH2, you'll find tons of articles. Here's just a few of the ones that are relevant to our mutation:

• Self-Reported Alcohol-Associated Symptoms and Drinking Behavior in Three ALDH2 Genotypes Among Japanese University Students-
• Self-Reported Flushing and Genotypes of ALDH2, ADH2, and ADH3 among Taiwanese Han
  -
• Relevance of Both Daily Hassles and the ALDH2 Genotype to Problem Drinking among Japanese Male Workers
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• Accumulation of Hemoglobin-Associated Acetaldehyde With Habitual Alcohol Drinking in the Atypical ALDH2 Genotype
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• Alcohol and Aldehyde Dehydrogenase Gene Polymorphisms Influence Susceptibility to Esophageal Cancer in Japanese Alcoholics
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• Clinical Characteristics and Disease Course of Alcoholics with Inactive Aldehyde Dehydrogenase-2
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• A Novel Polymorphism (-357 G/A) of the ALDH2 Gene: Linkage Disequilibrium and an Association With Alcoholism
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• Studies on the Enzymology of Aldehyde Dehydrogenase-2 in Genetically Modified HeLa Cells

Those last two are of great interest to me, so I must say thankyou for indirectly bringing them to my attention. But anyway, you can see that this particular mutant is something that has been extensively studied. Your skepticism of that one study is well placed, but the plethora of others shows quite clearly that this particular allele -- both its presence and prevalence -- has become a major focus on studies for alcoholism, and it's not really much of an issue whether or not it's there.

theyeti

[ February 11, 2002: Message edited by: theyeti ]</p>

phaedrus

hey theyeti,

Thanks for that. Did notice that the paper was about the linkage to cancer but came across it as i was trying to search for the original study which talks about most of the asians having the allele and since it seemed the most recent study was concentrating on it.

Anyhows as you would had noticed while part of my query was talking about the "fact of allele itself", the other part is about the sample size and as to which countries they are referring to by the term "asian". Going by most of the titles, it seems to refer mostly to far-east asian countries and japan.

Could you provide a link to the original study in this regard? Want to quantify “most Asians” and find their definition of “asian”.

theyeti

Paedrus, I don't know what the first study was that found this variant, but it goes back at least to the 1970's and prossibly earlier. You won't find the journal article online; it's very difficult to find any full text journals prior to 1995, and bascially impossible to find any prior to 1990. If you want to find the particular paper, you will (gasp!) have to go to a university library. Here are the results of a <a href="http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?db=PubMed&cmd=Display&dopt=pubmed_pubme d&from_uid=7182684" target="_blank">PubMed</a> search using the "related articles" button over and over. There are lots of papers about ethnicity and alcohol tolerance. The oldest one I could find is this one: Wolff PH., <a href="http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=500791 2&dopt=Abstract" target="_blank">Ethnic differences in alcohol sensitivity.</a> Science 1972 Jan 28;175(20):449-50. There's no abstract (no surprise there), so if you want to find out anything about this study, you'll have to look it up at the library. If you're lucky, it won't be off-site like a lot of 1970's journals are. You can then look in the references for anything earlier. Hope this helps.

theyeti

Coragyps

If it's in Science after 1880, it's online for subscribers, and I'm one. PM me, phaedrus, and I'll figure out how to get you a copy.
Coragyps

[ February 13, 2002: Message edited by: Coragyps ]</p>

phaedrus

guys...thanks for your help...i will look around for the studies