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Do my genes increase my likelihood of developing a disease?

23.NOV.2023

Written by Anna Sanniti

Reviewed by Wendi Gill, CGC

Most diseases we are familiar with are known as ‘multifactorial diseases’. Multifactorial diseases are not caused by one thing (think ‘multi’ = many, and ‘factorial’ = factors). A combination of factors like age, genetic makeup, and factors such as our diet, lifestyle, and environment causes them. In this article, we discuss what it means to be told that we have a genetic predisposition for a disease. You may sometimes hear this referred to as a ‘genetic risk’.

  • What is a genetic predisposition?

  • Are lifestyle factors different from genetic risk?

  • What does it mean if I am told that I have a genetic variant associated with a disease?

What is a genetic predisposition?

Genetic research is always looking for discoveries linking a genetic variant (a genetic change) to a disease. It helps us understand more about the disease and develop new treatments. 

A genetic variant is a difference we see in the genetic code within DNA from one person to the next. For example, some individuals may have an ‘A’ at one position, while others may have a ‘G’. 

Usually, this type of research is carried out on thousands of people from two different groups: one group of people will have the disease, and the other group will not. The scientists will analyze and compare these two groups. This is to determine whether some genetic variants appear more often in the group of people with heart disease. If a genetic variant is found, these are studied further to validate them and a link with the disease is made. [1]

Let’s go back to the original group of people in the study:

  • There will be people in the group of patients with heart disease who do not have this variant. Their heart disease could be caused by diet or lifestyle factors, or by a combination of other genetic variants that may not yet be known.

  • There will be people in the group of healthy volunteers who do have this variant but do not have heart disease.

Illustration showing the likelihood of heart disease in those with and without gene variant.

The above shows that a genetic predisposition is not the only factor that decides the development of a disease in a person, many factors are involved. Knowing that you have a genetic variant is just a piece of the puzzle. [2] Understanding the different pieces can allow you to seek appropriate care. This can help further reduce your chances of developing the disease. This can be empowering for you and your healthcare provider.

Are lifestyle factors different from a genetic predisposition?

Lifestyle factors such as our diet and environment can change over time. Our genetic predisposition remains the same. Multifactorial diseases are often caused by a combination of our unique genetic make-up and lifestyle factors. An example of this can be:

  • Having variants that may influence cholesterol levels

  • Eating a diet high in saturated fat

  • The development of heart disease

Lifestyle factors such as diet and exercise may increase the chances of developing a disease more than any risk.

What does it mean if I am told I have a genetic variant associated with a disease?

Somebody with a genetic variant associated with a disease has a higher chance of developing that disease. If testing does reveal that you have a variant, you should talk to your healthcare provider. Having this knowledge empowers you and your provider to make decisions about your healthcare. Still, don’t forget the two groups of people in the study described above! Being told you have a genetic variant associated with a disease does not necessarily mean that you have or will develop the disease in the future. Many healthy volunteers in the study were identified to have a disease-causing variant but had no signs of the disease.

Let's recap

In summary, receiving information about your genetic predisposition:

  • is not a diagnosis.

  • is not a prediction of a future diagnosis.

  • is a piece of the puzzle that should be empowering.

  • can help you, together with your healthcare provider, to better plan your lifestyle and medical care that can help reduce your chances of developing the disease or allow for more treatment options earlier.

Knowledge Hub

References

1. National Human Genome Research Institute Educational Resources. GWAS. Online: Genome.gov

2. National Human Genome Research Institute Educational Resources. GWAS. Online: Genome.gov