How does genetic risk affect your health?

What does genetic risk mean?

We all have DNA inherited from our parents. DNA carries genetic information that tells our cells how to function and grow.

Each person’s DNA contains small differences that give us unique traits, such as hair colour or height. Some DNA differences can be linked to an increased chance of developing certain diseases. This tendency to develop certain diseases based on your DNA is known as genetic risk.

Having a genetic risk does not mean you will get a disease. Other factors such as your environment or lifestyle can also influence your chance of getting a disease.

What does family history mean?

You have a family history of a certain health condition or disease if one or more members of your family have had a diagnosis.

Having a family history of a disease can indicate an increased genetic risk. But this isn’t always true. For example, your family member may have developed a disease because of environmental rather than genetic factors.

You may wish to have genetic testing to find out if you’ve inherited certain gene differences (variants). Ask your doctor which tests are available.

How does genetic risk affect your health?

You may inherit a genetic variant in a single gene that causes, or significantly increases the risk of, a monogenic disorder. These conditions are usually linked to a change in one specific gene. Some examples of monogenic disorders are:

• sickle cell disease
• cystic fibrosis
• Huntington’s disease

You may also inherit a combination of genetic variants across many genes. Each variant may only have a small effect on its own, but together they can influence your overall chance of developing certain conditions. This is known as polygenic or multifactorial risk.

Examples of multifactorial disorders include:

• types of cancer
• heart disease
• diabetes
• osteoporosis

Multifactorial (or complex) disorders are often also influenced by environmental factors as well as genetic risk.

What genetic testing can I have?

Genetic testing, also known as genomic testing, is performed to help determine if you’re at an increased risk of developing a certain disease in the future. Depending on the type of genetic testing you have, it might involve a sample of blood or tissue being taken. Some genetic tests can be done using saliva (spit) samples or from a swab taken from your mouth.

You may wish to have genetic testing if a certain disorder runs in your family and you’re concerned about your risk. For monogenic disorders, single-gene testing may be available. This can look for genetic changes in single genes that are associated with certain disorders. The test is usually a blood or saliva sample. It can tell you whether you’ve inherited the genetic change that can increase your risk for a disorder.

For complex disorders, your risk may be assessed using a polygenic risk score. It’s calculated by looking at many small differences across your DNA and comparing them with patterns seen in people with and without the condition.

A polygenic risk score can give an indication of your risk, but it is an estimate. A polygenic risk score can’t definitively predict whether you’ll develop a condition or not.

Remember that it’s entirely up to you whether you have genetic testing or not. If you’re concerned about your genetic risk, speak to your GP.