Author: Gary Jackson

Genetics of Alcohol Use Disorder National Institute on Alcohol Abuse and Alcoholism NIAAA

Is there any scientific evidence that your genes may predispose you to have an alcohol dependency if your parents or grandparents did? While many studies have been done, and experts agree that there is a hereditary connection, genetics is not the only factor, and we don’t quite know the full impact it has on alcoholism. 1The terms “alcoholism,” “alcohol dependence,” “alcohol abuse,” and “problem drinking” frequently overlap in the alcoholism literature; therefore, the terms are used in this article as they were used in the original studies cited. Alcohol use disorder (AUD) often seems to run in families, and we may hear about scientific studies of an “alcoholism gene.” Genetics certainly influence our likelihood of developing AUD, but the story isn’t so simple. Genetic disorders are diagnosable conditions directly caused by genetic mutations that are inherited or occur later in life from environmental exposure.

  • Finally, the largest twin study of women found that concordance for alcoholism was significantly greater among MZ than among DZ twins (i.e., 32 and 24 percent, respectively) (Kendler et al. 1994).
  • For example, five adoption studies have investigated the relationship between alcoholism or problem drinking in biological parents and alcoholism in their adopted-away sons.
  • Behavioral-genetic researchers have attempted to identify genotype-environment interactions for alcoholism by using adoption studies.
  • Although the phenotype analyzed by Ge and colleagues (1996) may not be of direct interest to alcohol researchers, the methods and findings from this study clearly illustrate how genotype-environment correlations might affect complex behavioral phenotypes.

Your genetic risk refers to the likelihood that specific genes or genetic variants passed down to you will lead to a particular condition. Living in a household where you’re regularly exposed to parental alcohol use can also increase your chances of AUD, regardless of your genetic predisposition. A review of studies from 2020, which looked at a genome-wide analysis of more than 435,000 people, found 29 different genetic variants that increased the risk of problematic drinking. There is evidence that heavy episodic (binge) drinking, which results in
exposure of tissues to high levels of alcohol, is particularly harmful81, 87, 88.

The Role of Environment in Alcoholism

Ge and colleagues (1996), however, recently demonstrated how genotype-environment correlations could be investigated using an adoption study approach. These researchers investigated the factors contributing to the etiology of antisocial behavior among children. For many studies (e.g., if the numbers of MZ and DZ twin pairs in the study differ greatly), however, these simple calculations are inadequate, and more complex models must be used to estimate the contributions of all three types of factors to the behavior studied.

  • The genes with the clearest contribution to the risk for alcoholism and
    alcohol consumption are alcohol dehydrogenase 1B (ADH1B) and
    aldehyde dehydrogenase 2 (ALDH2; mitochondrial aldehyde
    dehydrogenase), two genes central to the metabolism of alcohol (Figure 1)20.
  • According to the DSM-5-TR, the more relatives you have living with AUD and the closer they are to you in relation, the higher your individual genetic risk becomes.
  • The results of such analyses have consistently found that the heritability of the risk for alcoholism lies between 0.5 and 0.6 for men.
  • Your genetics can influence how likely you are to develop AUD, but there’s currently no evidence of a specific gene that directly causes AUD once you start drinking.

These formulas rely on previously determined correlation coefficients, which are numerical ways of describing the relation of the behavior under study to the environmental or genetic factors hypothesized to underlie that behavior. A correlation coefficient of 1 describes a perfect positive correlation (e.g., the presence of a particular gene means that a particular behavior, such as problem drinking, will almost certainly be seen in the subject). It is likely that, as for most complex diseases, alcohol dependence and AUDs
are due to variations in hundreds of genes, interacting with different social
environments. An additional challenge in the search for genetic variants that affect
the risk for AUDs is that there is extensive clinical heterogeneity among those
meeting criteria. Because the diagnosis of an AUD requires the presence of a set of
symptoms from a checklist, there are many different ways one could meet the

Alcohol Use Disorder and Genetics

Conversely, paternal alcohol abuse did not affect the adopted-away daughters’ risk of alcohol abuse, suggesting that genetic effects might be gender-specific. Finally, the largest twin study of women found that concordance for alcoholism was significantly greater among MZ than among DZ twins (i.e., 32 and 24 percent, respectively) (Kendler et al. 1994). The results of both adoption and twin studies have suggested that genetic influences affect type II alcoholism more strongly than type I alcoholism. For example, in the Stockholm Adoption Study, genetic factors were estimated to account for 90 percent of the risk for type II alcoholism, but for less than 40 percent of the risk for type I alcoholism (Cloninger et al. 1981).