Alcoholism and Genetics: Is Alcoholism Hereditary?

Saima Andrabi   by Saima Andrabi, MS, Clinical Biochemistry    Last updated on July 26, 2019,

alcoholism and genetics

 

Alcoholism or Alcohol use disorder (AUD) is an illness characterized by an inability to control excessive alcohol drinking. Alcohol is a highly addictive substance that can cause harmful long-term effects on a person’s body and mind besides affecting his or her ability to think, feel and act. Most of the people suffering from this disease consume alcohol so as to escape or relax from stress-filled days, turn an occasional release into a necessary occurrence to feel good, increase positivity to feel good and want to get accepted among peers.

Early stages of alcohol abuse set the base for dependency. In the beginning, an individual may notice an increase in drinking to suppress negative feelings but this soon spirals into a dependency affecting the job performance, daily routines and behaviors. Dependence occurs when an alcoholic needs to consume alcohol to avoid withdrawal symptoms like nausea and tremors.

Is Alcoholism Hereditary?

There is scientific evidence that alcoholism has a genetic component, nevertheless the actual gene that may cause it, is yet to be identified. Similarly, studies of laboratory animals as well as human test subjects have indicated that genetic factors have a major role in the development of alcoholism. According to the American Academy of Child & Adolescent Psychiatry, children of alcoholics are four times more likely to become alcoholic than other children whose parents are non-alcoholic. However, environmental factors could be a factor in many of those cases as well.

Alcoholism and Genetics

Our genetic structure determines all our human traits. Our DNA speaks a lot about our physical characteristics (such as eye color) and also our behavioral characteristics (such as aggression). These genes are passed on to us by our parents. Besides behavioral traits, parents can pass a predisposition towards alcohol abuse and addiction to their children. Among those abusing alcohol, people who are genetically predisposed to alcoholism have a higher risk of developing an AUD. Even though people can inherit alcoholic tendencies from their parents, the development of an alcohol use disorder is also dependent on social and environmental factors. Some people who have inherited genes making them susceptible to alcoholism are responsible drinkers or never drink alcohol throughout their life. Research has proved that genes are responsible for about half of the risk for alcohol use disorder (AUD). Therefore, only genes are not responsible for deciding whether someone will develop AUD or not. Besides, environmental factors, as well as gene and environment interactions account for the remainder of the risk.

Genetics contribute 50 % of the primary reason for alcohol use disorder. If a person is predisposed to metabolize alcohol in such a way that the pleasurable effects are more prominent than feeling nauseous, overheating, or experiencing mood swings, the person will be more likely to develop alcohol use disorder.

According to a 2008 study conducted by the National Institute on Alcohol Abuse and Alcoholism (NIAAA), genetic factors account for 40-60 % of the variance among people who struggle with alcoholism. Since then, some specific genes that contribute to AUD have been found, and they correlate with the development of the reward centers in the brain.

The phenotypic expression of genes is complex. For example, a person may have one parent with blue eyes and other parent with brown eyes, so they have genes for both eye colors, but only one eye color among the two will be expressed in the offspring. However, strong genes are the exception to this rule, and a gene responsible for the movement of gamma-amino butyric acid (GABA) in synapses between neurons appears to be a strong gene linked with a higher risk of alcoholism. The reason behind this is still unknown but precisely, this genetic sequence can ultimately influence the outcome for a person.

The “Alcoholic Gene”

There is not only a single gene responsible for alcoholism. Instead, there are hundreds of genes in a person’s DNA that may increase the risk of developing an alcohol use disorder. Identifying these genes is difficult because each has a small role to play in a much larger picture. Although, studies have shown that certain combinations of genes have a strong relationship to alcoholism. There are also some behavioral genes inherited that could influence a predisposition for alcoholism. Some mental illnesses, like depression and schizophrenia, are more common in people with a family history of these disorders. People with mental illness have a higher risk of turning to substance abuse as a way of coping. Mental disorders can be hereditary or environmental, which partially clarifies the complex link between genetics and addiction.

How Do Genes Influence Alcohol Use Disorder?


Alcohol use disorder (AUD) often seems to run in families, and we may hear about scientific studies of an “alcoholism gene.” Genetics certainly influences our probability of developing AUD, but the phenomenon isn’t so simple. Research has proved that genes are responsible for about half of the risk for AUD. Therefore, genes alone do not determine whether someone will develop AUD or not. Many genes play a role in a person’s risk for developing AUD. There are genes that may increase a person’s risk, as well as decrease that risk, directly or indirectly. For example, some people of Asian descent carry a genetic variant that alters their rate of alcohol metabolism and therefore results in symptoms like flushing, nausea, and rapid heartbeat when they drink. Many people who experience these effects avoid alcohol, and are at a low risk of developing AUD.

Heredity and Alcoholism

Although children of alcoholics have an increased chance of struggling with alcohol abuse later in life, a survey in 2011 found that less than half of them actually developed alcohol use disorder. This could be explained, in part, by not inheriting the genes for AUD, or it could be explained by the environment that led to a specific expression of those genes. Statistically, a family history of alcoholism is associated to an increased risk of genetic predisposition to alcoholism, depending on how close the relatives are to each other. Children who have only one parent with alcohol use disorder are 3-4 times at increased risk of becoming an alcoholic themselves. However, having more relatives, such as aunts, uncles, grandparents, and other family members with alcohol use disorder does not have the same strong association. In fact, this relation can influence whether or not a person inherits genetic mutations that predispose them to alcohol use disorder or not. Besides, growing up in an environment influenced by addiction can also predispose a person to the condition.

Alcohol consumption in the United States is legal for people who are 21 years or older, although performing specific tasks like driving or operating heavy machinery are banned based on blood alcohol content (BAC). Social drinking is common in the United States, and many people drink to reduce stress.

Men usually drink more alcohol than women. The Centers for Disease Control and Prevention (CDC) observed that between 1997 and 2015, twice as many men drank heavily at least one day per month compared to women. However, women are beginning to drink alcohol much more commonly. When people are exposed to large amounts of an addictive substance over an extensive period of time, it is likely that this substance abuse will rewire the user’s brain to desire the substance. Even without a genetic component present, a person can still inherit a predisposition to AUD due to the culture they grow up in.

Symptoms of Heredity Alcoholics

Alcohol abuse can result in a long list of negative side effects and behaviors including:

Genetic vs. Hereditary Alcoholism

People often wonder if alcoholism is hereditary or genetic. However, it is important to know the difference between the two terms as both are not same. Genetics includes a person’s DNA. A condition that is genetic can also be hereditary, but there will always be a mutation in the genome. Heredity refers to a mutation in a person’s genes inherited from generation to generation. As it relates to alcoholism, genes are half responsible for AUD. While children of alcoholics are twice as likely to be at risk for AUD, less than half of them actually struggle with the disease. However, some other underlying factors influence the choice to engage in alcohol consumption.

The Genetics of Alcohol Use Disorder

To understand how the risk of AUD is passed down from generation to generation, scientists have examined genetics in family lineages to identify potential hereditary causes of this chronic disease. Medical researchers have reported 11 pairs of genes that are associated in some way with a risk of excessive drinking and developing compulsive behaviors around alcohol. Based on research using mice, the team found these genes in groups of humans. Among all of those 11 pairs were also associated with neuropsychiatric disorders apart from AUD, like Parkinson’s disease, schizophrenia, bipolar disorder, anxiety, and cocaine addiction.

Some of the genes associated with increased risk of developing AUD include: 

ADH1B Gene

This gene has a low prevalence in European, specifically Caucasian, population, but is very prevalent in East Asians. According to one report almost 70 % of East Asians had this gene. Variants of this gene are linked with the alcohol flush reaction, which can cause a person to feel hot and sweaty, make their face and body flush, and increase feelings of sickness. Only about 5 % of European population feature this gene, which is involved in the liver’s ability to metabolize alcohol to acetaldehyde and then to acetate. When there is an excess acetaldehyde not readily metabolized into acetate, a person develops the flush reaction, which is uncomfortable. It is considered a deterrent for alcohol use disorder; therefore, in population that have a lower frequency of this gene, like Europeans, there is an increased risk of developing AUD, with fewer genetic deterrents.

GABRB1 Gene

According to some studies, mutations of the GABRB1 gene have found to increase the risk of AUD because of changes to gamma-amino butyric acid (GABA). Since alcohol changes how much GABA is available to the brain, inducing relaxation and relieving anxiety or stress, mutations in this area of brain results in less GABA production which may prompt a person to abuse alcohol to feel better (the self-medication hypothesis).

Beta-Klotho Gene

This gene is linked to drinking less instead of experiencing pleasant feelings from excessive drinking. People with the beta-Klotho gene are able to control their drinking, usually consuming one or two drinks and then successfully stopping. This gene is triggered by two hormones which can determine whether the person also has a sweet tooth, preferring sugary tastes. People lacking this gene are less likely to control their urge to keep drinking alcohol. These are only three of the numerous genes found to be associated with substance abuse, including AUD. Some genes can help a person regulate their alcohol consumption or avoid the substance overall while others increase the person’s risk of abusing alcohol.

Gene expression is affected by environment. If a person grows up in a family with a parent who abuses drugs, struggles with mental illness, suffers a major financial setback or similar stress, and the child has a gene associated to alcohol use disorder, they are very much prone to develop this condition later in life. In such situations, prevention and education programs can address this risk as part of regular medical checkups. Genetics is understood to be a component of AUD, but not the only cause.