Polygenic Scores This website is being used for research purposes only.

A polygenic score is used to estimate a person’s risk for a particular health outcome, such as disorders like alcohol use disorder, based on their genetics.

Knowing whether your genetic background increases your risk to develop certain disorders may help you make important decisions about your health.

Genetic Variation

Everyone has a genetic code that they inherit from each of their parents. Each person’s genetic code is made up of units of information, that contain instructions the body needs in order to function.

Most of the genetic code is identical between individuals. However, differences in the genetic code are called genetic variants.

Genetic variants contribute to traits that make us unique such as eye color, height, and taste preferences.

Genetic variants can also impact our risk of certain disorders — these are called risk variants.

Risk Variants

To discover risk variants, scientists compare the genetic codes of people without a disorder to people with a disorder.

If a genetic variant occurs more frequently in people with a disorder, it is associated with increased risk.

If a genetic variant occurs more frequently in people without a disorder, it is associated with decreased risk.

Risk variants can increase or decrease a person’s risk of disorder and each can have different magnitudes of impact.

Some risk variants have a large impact on risk and some risk variants have a small impact on risk.

← small impact large impact →

A single, small impact variant has little impact on risk, but many of them together have a larger impact.

A polygenic score looks at all of these small impact risk variants at once to estimate a person’s risk for a disorder.

Polygenic Score Calculation

To calculate a person's polygenic score for a particular disorder, scientists add up the total number of risk-increasing and risk-decreasing variants, along with their magnitude of impact.

A polygenic score tells you how your risk for a disorder compares to others.

Scientists can determine polygenic scores for a whole population.

Some people will have a higher or lower score, depending on their number of risk-increasing or risk-decreasing variants, and the magnitude of impact of each variant.

People with an approximately even number of risk-increasing and risk-decreasing variants have average scores.

People with more risk-increasing variants have higher scores.

People with more risk-decreasing variants have lower scores.

Polygenic Score Interpretation

Most people have average genetic risk of disorder.

Your score can be higher than average meaning that you have increased genetic risk of disorder compared to most people.

If your polygenic score is in the 95th percentile, you do not have a 95% chance of developing the disorder. Rather it means that — out of 100 people — your polygenic score is higher than 95 people and the same or lower than 5.

Your score can be lower than average meaning that you have decreased genetic risk of disorder compared to most people.

If your polygenic score is in the 5th percentile, you do not have a 5% chance of developing the disorder. Rather it means that — out of 100 people — your polygenic score is higher than 5 people and the same or lower than 95.

Polygenic Score Application

Polygenic scores may be useful tools to assess risk for many important health outcomes, including substance use disorders and mental health conditions, all of which are influenced by our genes.

Researchers are still in the process of finding all the genes that influence alcohol use disorder. So far, they have only identified some of the specific genetic variants that contribute to the development of alcohol use disorder. Right now polygenic risk scores only account for up to 5% of the total things that can contribute to the development of alcohol problems. How accurately they predict outcomes can also vary across people with different racial/ethnic backgrounds. Minorities tend to be underrepresented in genetic research, so polygenic risk scores may not be as accurate for people with non-European ancestral backgrounds.

Understanding Alcohol Use Disorder

Alcohol use disorder is diagnosed when an individual has trouble stopping or controlling their alcohol use despite it causing serious problems at home, at work, or to their health. More than 107 million people around the world have an alcohol use disorder. Excessive alcohol use can cause liver disease, digestive problems, heart problems, neurological complications, and increased risk of cancer. Nearly 100,000 people die as a result of alcohol problems every year in the United States. Both genes and environments influence a person’s risk of developing an alcohol use disorder.

DNA is not destiny — additional factors influence your risk

Even though you can’t change your genetics, there are ways to reduce your risk of developing an alcohol use disorder.

Strategies for cutting down alcohol use:

Keep track of how much you drink - Count and measure your drinks

Find alternatives, such as new hobbies or friendships, or socialize with others who do not drink

Take a break from drinking alcohol or choose not to drink at all sometimes, even though others are drinking

Set goals for how many days you will drink each week and how many drinks you will have on those days

Avoid places and people that trigger drinking and do not keep alcohol at home

Learn how to say “no” when offered a drink

Strategies for reducing the harmful impact of alcohol use:

References

  1. Hannah Ritchie and Max Roser (2018) - "Alcohol Consumption". Published online at OurWorldInData.org. Retrieved from: https://ourworldindata.org/alcohol-consumption [Online Resource]
  2. Esser MB, Sherk A, Liu Y, et al. Deaths and Years of Potential Life Lost From Excessive Alcohol Use — United States, 2011–2015. MMWR Morb Mortal Wkly Rep 2020;69:1428–1433. DOI: http://dx.doi.org/10.15585/mmwr.mm6939a6
  3. Mayo Clinic Staff. (n.d.). Alcohol use disorder—Symptoms and causes. Mayo Clinic. Retrieved July 19, 2021, from https://www.mayoclinic.org/diseases-conditions/alcohol-use-disorder/symptoms-causes/syc-20369243
  4. Understanding Alcohol Use Disorder. (2021, April). National Institute on Alcohol Abuse and Alcoholism (NIAAA). https://www.niaaa.nih.gov/publications/brochures-and-fact-sheets/understanding-alcohol-use-disorder