Are there genes that repel or discourage some people from imbibing with wine, beer, whisky, or other alcoholic drinks? For example, does a small amount, say two ounces of wine cause a fast heart beat, flushing, or nausea? Does your child react more positively toward alcohol or reject it? If you have a relative who is an alcoholic, chances are some of your children may have inherited the gene for alcoholism. Check out the May 23, 2011 news release, “Heredity behind subjective effects of alcohol.”
Locally in the Sacramento and Davis area, U.C. Davis studies alcoholism–in rodents. See, UC Davis Health System Feature Stories. But what about the possibility of genes that raise the risk of alcoholism in humans? For that you have to divide type I alcoholism from type II alcoholism.
Scientists have long known that people who have a close relative with alcohol problems themselves run an increased risk of starting to abuse alcohol. The reason for this has not been known, but a new study from the University of Gothenburg, Sweden, provides part of the answer. The study shows that people who have a close relative who is an alcoholic react more positively to alcohol than other people.
The study has been published in the scientific journal Alcohol: Clinical & Experimental Research, and is the first to have investigated a large group of people who have a close relative with type I alcoholism. Previous research in the field has been based on a more limited population, such as sons of alcoholic fathers. Check out the journal, Alcoholism: Clinical and Experimental Research – Journal Information.
Also see the articles, Heavy Drinkers Outlive Nondrinkers, Study Finds – TIME, and Study: Binge drinking tied to memory loss in college students.
There are two types of alcoholism, type I and type II. Type I alcohol abuse depends to a large extent on the interaction of genetic factors with the environment, such as social environment and life events, while type II alcohol abuse involves a large genetic risk of developing alcohol addiction, independent of environment.
“The study is unique in the way in which we have studied how children of type I alcoholics experience the effects of alcohol and compared this with the experiences of the control group, which consisted of people who had no history of alcohol abuse in the family.
The group of people who were children of type I alcoholics were healthy and had no mental health problems, and they did not have alcohol problems themselves”, says Anna Söderpalm-Gordh, scientist at the Sahlgrenska Academy, according to the May 23, 2011 news release.
The scientists gave moderate amounts of either alcohol or placebo in the form of juice to a group of 51 participants, 34 men and 17 women. The drink that any participant received was determined at random. Twenty-nine of the participants were members of the control group, while 22 were members of the group for whom a member of the family had type I alcoholism. Members of both groups then described how they experienced the effects of the alcohol.
The scientists discovered that participants with a family member with type I alcoholism reported more positive and more stimulating effects from drinking alcohol than participants in the control group. These individuals also wanted to drink more alcohol than those in the group without any heredity effects. This supports the hypothesis that children of type I alcoholics inherit some form of positive experience of drinking alcohol.
“These results show that some of us are more responsive to the rewarding effects of alcohol: we react to alcohol more strongly and more positively than others. This can, in turn, lead to increased consumption and a greater risk of alcohol abuse.
The results also suggest that children of type I alcoholics, who have been considered to run a smaller hereditary risk of developing alcohol addiction, may be in the danger zone for developing alcoholism”, says Anna Söderpalm-Gordh.
She believes that these results are important, particularly against the background of the fact that around 40% of the population of Sweden have a close family member who has problems with alcohol.
“Be aware of how you react to alcohol. You should consider cutting down and not drinking as much as other people if you notice that you experience alcohol as more positive than your friends,” she says, according to the news release, and continues:
“Each person’s individual experience of alcohol is an important tool in understanding why certain people develop alcoholism and it may be a marker in itself for how an individual’s alcohol consumption may develop. Our discovery is part of the preventative work that can help a certain group of people who run the risk of drinking too much alcohol.”
If you are surrounded by an environment that encourages drinking, for example, on campuses or when you go out with friends to local night life events, how much alcohol do you like to drink with your food?
And has the wine or beer drinking (or preparing) tradition been in your family for generations? Would you rather cook with wine or drink it? How do you know whether you’ve inherited a specific type of gene/allele to protect you against alcoholism by making alcoholic drinks taste pretty bad in your mouth or smell like some type of cleaning chemical?
Can you predict which groups in your town will drink the most without becoming violently ill fastest? Scientists are studying why some ethnic groups drink far less than others and whether the environment influences drinking habits or whether genes override the environment.
Does your part of the USA encourage drinking among certain age groups or even specific ethnic groups? If not, why? And if so, what’s the payoff for drinking socially? Let’s look at some scientific ethnic studies on genes and alcoholism.
Does A Specific Percentage of Middle Eastern Genes Protect Somewhat Against Alcoholism?
Scientists surmise that maybe some of the answers turn up in studies the genes of some Eastern European Jewish families who have very low rates of alcoholism even though for centuries they lived next to neighbors in Russia or Poland who drank more alcoholic drinks because it tasted differently to one group than the alcohol did to the other group. Do your genes determine whether you want to drink an alcoholic beverage based on how it tastes and smells to you? How do your genes keep you from drinking too much?
Do you have the gene variation that protects against alcoholism? The two peoples most likely to have gene variations that protect against alcoholism are Jews descended from ancestors who lived in Eastern Europe, peoples genetically related to them, and other Middle Eastern peoples.
Also see the article, Health-Related Effects of Genetic Variations of Alcohol – NIAAA. According to this study, alcohol avoidance is not just about taste, it’s about symptoms experienced after drinking a small amount of alcohol by some who immediately feel a rapid heartbeat and nausea after drinking a small amount of alcohol. Alcohol metabolism is one of the biological determinants that can influence drinking behavior and the development of alcohol dependence and alcohol-induced organ damage (Yin and Agarwal 2001).
Oxidative alcohol metabolism depends on two key enzymes—alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH). ADH converts alcohol to the highly toxic metabolite acetaldehyde, which then is metabolized by ALDH to acetate and eventually to carbon dioxide (CO2) and water.
For both ADH and ALDH, several variants (i.e., isoforms) exist that differ in their ability to break down alcohol and acetaldehyde, respectively. For example, certain ADH isoforms are particularly active and rapidly break down alcohol to acetaldehyde. Conversely, certain ALDH isoforms have very low activity and break down acetaldehyde slowly.
In both of these cases, acetaldehyde will accumulate after alcohol consumption, exerting its toxic effects by causing a flushing syndrome characterized by facial flushing, nausea, and rapid heartbeat. These effects deter people from alcohol consumption and therefore have a protective effect against alcoholism. How do you know whether you have the gene that keeps you from drinking alcohol by making you feel sick when you start to drink alcoholic beverages?
Could you have inherited a gene that protects you from becoming alcoholic or drinking irresponsibly? According to a study from the American Journal of Psychiatry, “Alcohol and ADH2 in Israel: Ashkenazis, Sephardics, and Recent Russian Immigrants.” (See, the American Journal of Psychiatry 159:1432-1434, August 2002.) There’s an old Yiddish saying, “Shikka as a goy.” It means “drunk as a non-Jew.” And this saying, common in 19th century Russia compared drinking habits between Russians and Jews living in Russia (or Poland, Lithuania, Latvia, or Belarus).
What did it really mean? It meant if someone got drunk, it usually would be someone not from a Jewish family? Why? Because in those days, drinking alcohol at least in excess was likely to make the person with the most Middle Eastern (or Asian) genes feel flushed, nauseous, and develop a rapid heartbeat. Whereas with others without the gene, drinking created other changes in behavior rather than flushing and nausea.
Some other groups may also have inherited such genes. It’s not by accident, for example, that in the Middle East Islam forbade drinking alcohol. People with perhaps a certain percentage of Middle Eastern genes just don’t drink very much (unless they’ve also inherited lots of European genes as well.) The same can be said for people of Far Eastern descent and some African Americans.
Who lacks genes that warn them not to drink to much? Possibly Native Americans who diverged from Far Eastern peoples tens of thousands of years ago, and Europeans who for thousands of years have fermented grains and grapes to make beer and wine. But with mixing of peoples, only you know whether you’ve inherited the gene that protects against alcoholism or whether alcoholism runs in your family.
This study, “Alcohol and ADH2 in Israel: Ashkenazis, Sephardics, and Recent Russian Immigrants,” indicates a protective role against heavy drinking in Jewish individuals, for the people who have the gene (allele) variation called ADH2*2, which may partially explain the low levels of alcoholism among people who have this genetic inheritance. An allele in genetics is either of a pair (or series) of alternative forms of a gene that can occupy the same locus (place) on a particular chromosome and that control the same character. For example, some alleles are dominant over other alleles.
Jews drink less than other Caucasians and have a higher prevalence of ADH2*2, an allele of an alcohol dehydrogenase gene that protects against heavy drinking. The relationship of ADH2 polymorphisms to lifetime maximum number of drinks per occasion was investigated in recent Russian immigrants to Israel (exposed to heavier drinking in their country of origin), other Israeli Ashkenazim, and Sephardim.
Seventy-five randomly sampled Israelis participated in a structured interview. ADH2 was genotyped for 68 subjects. ADH2*2 predicted less drinking; however, associations between ADH2 and drinking appeared to differ across the groups, consistent with differences in environmental exposure to heavy drinking.
The findings support a protective effect for ADH2*2 against heavy drinking in Jewish samples but also suggest the importance of environment. Future work should investigate interactions between genes and the environment in larger samples.
Jewish individuals have low rates of alcoholism (1), but little is known about influences on their drinking behavior, which may ultimately prove informative about alcoholism in general. Alcohol dehydrogenase is the principle enzyme for ethanol oxidation (2).
A functional polymorphism of the alcohol dehydrogenase genes, ADH2*2, has been shown to protect against alcoholism (2). ADH2*2 occurs in approximately 30% of Jewish individuals (3, 4), suggesting an explanatory role for ADH2 in drinking by Jews. However, the relationship of ADH2*2 to drinking in Jews varies (3, 4), possibly because of environmental influences or methodological variation. Studying contrasting Jewish groups with consistent methods should provide clarification, according to the study.
Russia’s per capita alcohol consumption level is very high, while Israel’s is very low. Until recently, the two main subgroups of Israeli Jews were Ashkenazim (European/Russian background) and Sephardim (Middle Eastern/North African background), who differ in drinking patterns (5). Since 1989, approximately 720,000 new immigrants from the former Soviet Union have arrived in Israel, now forming a third group, scientists noted in the study.
Recent Russian immigrants drink more than other Israelis (6). Therefore, ADH2*2 and drinking were studied in these three contrasting Israeli groups in that study. Scientists examined genotype and drinking in contrasting Jewish Israeli groups. Greater drinking among the Russian immigrants supported the validity of the drinking measure. The prevalence of the ADH2*2 allele was high, especially among Sephardim, and was found to protect against heavy drinking when scientists controlled for confounders.
The prevalence of a phenotypic trait or disease and an allele can both be elevated in a population subgroup for unrelated reasons. When this is undetected in a sample, population stratification can confound research results (11).
In this study, confounding due to population stratification was unlikely because we controlled for three main groups. Since a higher number of strata lowers the likelihood of confounding (12), the fact that the subjects in this study reported 18 different countries of origin minimized the likelihood of confounding due to population stratification.
In the recent Russian immigrants, exposed to an environment of heavy drinking before immigration, the effect of ADH2*2 appeared different, according to the study. Future studies with larger samples should specifically investigate the interaction of ADH2*2 and environmental influences on alcoholism. Such research may enhance the understanding of both genetic and environmental causes of disease.
New autosomal genetic studies on Jews reveals more news about ancient origins
Lots of new genetic studies in 2010 were conducted on Jewish peoples from various backgrounds in relation to health and nutrition as well as ancestral origins. It has been said that “people of the book” (am hasefer in Hebrew), referring to sacred tomes, also turns out to mean that geneticists now are able to read Jewish genomes like a history book using technology that looks at autosomal genes rather than Y chromosome or mtDNA that traces a person back to an ancient male or female ancestor thousands of years in the past. See the June 2010 Newsweek article, “The DNA of Abraham’s Children.”
According to an article in Newsweek, scientists researched “The Jewish HapMap Project. (All four grandparents of each participant had to have come from the same community.) As the scientists reported the findings in the American Journal of Human Genetics. Also see the article, Now Come Jewish Autosomal DNA Studies.
Also see the article, Analysis of Ashkenazi Jewish genomes reveals diversity, history. A Jewish genetic signature expressed in terms of autosomal DNA was predicted last year in a study titled, “A Genome-Wide Genetic Signature of Jewish Ancestry Perfectly Separates Individuals with and without Full Jewish Ancestry in a Large Random Sample of European Americans,” by Ann C. Need et al. (Genome Biology 2009, vol. 10). That study spoke of “near perfect genetic inference of Ashkenazi Jewish ancestry.”
Another study of Jewish autosomal DNA is “Genomic Microsatellites Identify Shared Jewish Ancestry Intermediate between Middle Eastern and European Populations,” published last year in BMC Genetics, vol. 10, by Naama M. Kopelman et al. It used 678 autosomal microsatellite loci in 78 individuals. Researchers note that on a large scale or on a small scale, there are three Jewish markers based on microsatellites forming part of a DNA fingerprint, although there are no so-called Jewish markers, but rather a sub-set of specific Middle Eastern markers, referring to a geographic origin rather to how serious one takes any given cultural tradition or religion.
According to one August 2010 article, Abraham’s Children: A Review, based on a June 2010 study and article by Gil Atzmon et al., “Abraham’s Children in the Genome Era: Major Jewish Diaspora Populations Comprise Distinct Genetic Clusters with Shared Middle Eastern Ancestry,” The American Journal of Human Genetics 86 (June 11, 2010) 850-859, “All Jewish populations, including Ashkenazim, resemble genetically the Druze, a Middle Eastern population that is still in its original place in Lebanon and Israel.
Syrian and Turkish Jews (Sephardim) most resemble Druzes.” The study also looked at Ashkenazi/Central and Eastern European Jews, finding they have a varying 30% to 60% of admixture with Europeans. But of course the rate of admixture is related individually to any particular family.
And not every family that exists in specific countries was sampled. You have to look at the number of people studied. The study also concludes Sephardic Jews have 8-11% North African (Berber) DNA. And also, according to the study, Italian, Syrian, Iranian and Iraqi Jews are the most inbred, according to that study.
So what does this mean for specific genes that protect against eating too much or drinking too much alcoholic beverages? Basically, people inherit genes/alleles that make certain foods and drinks either taste inviting or don’t taste like you’d want to sample a particular food or beverage.
For some people, no ethnic group in particular, even vegetables taste bitter at the back of the tongue, whereas other people enjoy chewing their raw veggies. So research continues on what peoples of the world eat or drink by preference or by genetic predispositions to the taste or feeling obtained from the food.