Genetic testing: Guiding medication choices

There isn't always a 'one-size fits all' solution to health problems. Some types of treatment or certain medications work well for one person but don't always have the same effect for another.

While medication is developed to address particular symptoms or problems in our bodies, many factors can influence how well those medications work and how our body responds.

One of those factors is our genes.

DNA contains our genetic code, the ‘blueprint of life' that tells the cells in our body what to do.

"As humans, most of our DNA is identical, but a small amount of our DNA is unique," explains Pharmacist and Bupa Health Insights Specialist Siobhan Kelliher.

"These genes dictate many things about you, including what colour eyes you have, your blood type or your height. Usually, the variations in our genes do not cause any problems with how our bodies work; however in some instances, these variations may be linked to health conditions."

There are many ways that genetic testing can be used to give us important information about our health.

For example, genetic testing can be used to help you understand the chance of passing a genetic condition on to your child, and genetic screening is done to screen newborn babies for rare genetic conditions.

People who have a family history of certain diseases (such a breast cancer) may be offered genetic screening to detect if they're at increased risk.

Some people may also have genetic variations that may influence how they respond to or metabolise (break down) medications.

Genetic testing could give your doctor insights that help them make prescribing choices for you. The study of how our genes impact our response to medications is called pharmacogenomics (PGx).

"Doctors can use pharmacogenomic information to assess how effective some medications might be or evaluate the risk of unwanted side effects,” says Kelliher. "This can help them make decisions about which medications may be best for you."

"Instead of trying multiple medications to find the right one, pharmacogenomics could help your doctor select the right medicine for you earlier," she says.

Genes are just one of the factors that can influence how your body responds to medications, but they can have an important effect.

Some people may process medications too slowly or too quickly. This might mean they are more likely to experience unwanted side effects, or that a medication may not work as well as expected.

PGx is a developing field, and we don't yet have insights about all medications. Based on the medication that you're currently using, your doctor can advise whether PGx testing is relevant for you. Insights from PGx testing can also be stored in your medical record to help guide future prescribing decisions.

Your doctor may consider pharmacogenomic testing if you:

• have recently been diagnosed with a condition or have been prescribed a new medication
• have medication which may not be working
• have experienced bad reactions or unwanted side effects from a medication
• are taking multiple medications or have another medical condition that could affect your response to medications
• are on a medication known to be influenced by genomics.

Your doctor might also want to understand how genomics might affect your response to medications you may need in the future.

PGx testing is available but not yet widely used in Australia.

Most PGx testing is not covered by Medicare. There are private providers of the test, but it's essential to ensure they are based in Australia and adhere to Australian health guidelines, laws and regulations.

If you're interested in PGx testing, speak to your healthcare team, who can help you decide if it's right for you.