What is pharmacogenomics and why is it important?

What is genomics? 

Remember that the ‘genome’ refers to the entire set of DNA instructions found within a cell – which consists of 23 pairs of chromosomes and roughly 20,000 genes. Genomics is the study of the entire genome – specifically how the genes in our DNA influence how our bodies work. 

Pharmacogenomics in action

After you take a drug, your body will need to break it down and get it to the area where it’s needed. The variation in our DNA can affect parts of this process, which may cause differences in how we break down and respond to drugs.  This is because DNA codes for proteins. Proteins are molecules that carry out important jobs in our bodies, such as: breaking down drugs, taking up drugs into cells, or reading messages from other proteins at the surface of cells. This is because small differences in our genetic make-up can cause slight variations in how proteins are made, which may affect how they behave[2].

Drug breakdown

Drugs are broken down by types of proteins called enzymes. Small differences in our genetic make-up may cause a drug to be broken down at different rates in different people. 

• If you break down a drug more quickly, then you will need more of the drug as it will not remain in your body for long enough to be effective. 

• If you break down a drug more slowly, then you will need less of the drug. This is to prevent too much of the drug building up in your body, potentially causing a bad reaction.

• In both scenarios, you could also be offered a different drug instead.

Drug uptake

Drugs are actively taken into the cell by transport proteins. Small differences in our genetic make-up may cause a drug to be transported at different rates in different people. 

• If there is lower uptake of the drug into the cell, then the drug can build up in other areas of the body, and may cause a bad reaction. This can also cause a weak response to the drug.

• If this is the case, then a lower dose or an alternative drug may be offered. 

Drug receptors

A drug may be targeting a protein found on the surface of cells, called a receptor. Small differences in our genetic make-up may mean that some people may have more and others may have fewer receptors.

• Many receptors on cells can cause a strong response to the drug.

• Fewer or no receptors on cells can cause a weak or absent response to the drug.

• In both scenarios, a different dose or an alternative drug may be offered based on the receptors that are present.

Drug hypersensitivity reactions

Some people may have a severe allergic reaction to some drugs, which can be due to genetic variation within genes that are involved in the immune system. These are less common but may also be included in a pharmacogenomic test[3].

How do insights from pharmacogenomic tests improve the treatment that we receive?

The genes analyzed during pharmacogenomic testing cannot be used to diagnose diseases, but will provide your health care provider with additional information to further personalize your current or future treatments. It has been estimated that up to 70% of harmful drug reactions are avoidable, and the significant room for improvement is of great interest to scientists.[4]. 

Pharmacogenomic testing helps healthcare providers to prescribe the most suitable treatment at the most appropriate dose, based on our unique genetic variation. Your genetics do not change, so these results can be used for years to come.