Wednesday, April 6, 2011

Bad Gene For Beer Lovers

As a scientist and science teacher I read a lot of science articles. I need to stay up to date on the latest scientific discoveries. Sometimes it supplements my teaching. But most of all, I find it an enjoyable distraction from the depressing cavalcade of assaults on the teaching profession.

Today I found a science blog posting by David Kroll, with the intriguing title: Bummer SNP doesn’t mix with beer for gastric cancer risk. For those of you who aren’t scientists, a SNP is a Single Nucleotide Polymorphism. Nucleotides are the components or subunits of DNA (Adenine, Guanine, Cytosine and Thymine). We all have some regions of DNA that are identical or virtually identical, particularly in critical genes, like those that help replicate DNA. We also have large regions of “junk” or less critical DNA that vary widely among individuals.

SNPs refer to genes or large regions of DNA that vary by only one nucleotide. While this might seem insignificant for a gene that has tens of thousands of nucleotides, it can lead to significant differences in how that gene functions. According to Kroll’s article, the Catalan Institute of Oncology (ICO) in Barcelona found that a SNP in the alcohol dehydrogenase (ADH1) gene correlates with a nine-fold increase in the risk of gastric cancer for heavy beer drinkers.

The research data showed that people with one SNP had a small, 30%, increased risk for gastric cancer. However, if they drank 60 g of alcohol per day (4 glasses of wine or 4 shots) their cancer risk went up by 75%. Even more remarkable than this, they found that beer had a much more dramatic effect than wine or hard liquor, increasing cancer risk 8.72-fold.

ADH is an important enzyme for metabolizing alcohol. ADH helps convert alcohol to the carcinogenic molecule acetaldehyde, which is then normally converted to acetate by the enzyme aldehyde dehydrogenase (ALDH). The SNP is thought to cause an increase in acetaldehyde, which might partially explain the higher cancer risk. However, this would not explain why beer was so much more carcinogenic to carriers of this gene than other forms of alcohol. The study was unable to answer this question, probably because the increased cancer risk is due to a combination of several factors, including the effects of the SNP, and perhaps phenols or nitrosamines (both carcinogens) that are found in beer.

Bummer Gene is A Reminder of the Dangers of Alcohol
So far, none of the companies that scan your DNA for risk factors are looking for this evil beer SNP. So beer drinkers, it may be years before you even have the opportunity to find out if you carry this bummer gene. Nevertheless, even for those who lack the bummer gene, Kroll correctly points out that there are a host of other diseases caused by or exacerbated by alcohol when consumed at a rate of 60g or more per day, including cancer of the colon, esophagus, liver and pancreas, as well as cirrhosis, not to mention all those empty calories. And then there’s the enormous carbon footprint from all that scotch and cognac you dipsomaniacs go through each week.

So, a skeleton walks into a bar and orders a beer and a mop.

John Kerry walks into a bar, and the bartender says, “So, why the long face.”

A teacher walks into a bar and gets fired for being unprofessional.

Here’s how. . .

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