An overview of Pharmacogenomic testing

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A study conducted in 2017 revealed that four out of five patients possess at least one genetic variation that could impact the effectiveness of commonly prescribed medications. While these individual genetic variations are uncommon and may not be evident in clinical trials, they become prevalent when considered collectively. Without undergoing genetic testing, these variations may remain undetected, compromising the safety of several prescribed drugs.

In the trial group, there is a flawed assumption that most individuals process drugs at a similar rate and in a similar manner. However, the reality is that a significant portion of the variation in drug reactions can be attributed to genetics. Pharmacogenomics, a branch of precision medicine, investigates the interactions between drugs and the genome, aiming to identify genetic markers that can indicate how a patient may respond to a particular drug.

These biomarkers are located on genes that influence various aspects of the body’s response to the drug. One category of such biomarkers is Pharmacokinetic (PK) biomarkers, which measure parameters related to the absorption, distribution, metabolism, and elimination of a drug. An example of a genetic difference in PK is found in variations on cytochrome P450 (CYP) genes. These genes encode enzymes crucial in the metabolism of at least 70 percent of prescription drugs. Notably, 75 percent of patients exhibit at least one genetic variant that makes them atypical drug metabolizers. Therefore, variations in drug-metabolizing enzymes are common among the patient population.

Pharmacodynamic (PD) biomarkers: Pharmacodynamics involves examining how a drug influences the body, encompassing aspects like receptor binding, chemical interactions, and receptor sensitivity.

Human leukocyte antigen (HLA) biomarkers: Human leukocyte antigen (HLA) is an immune protein situated on the surface of white blood cells. HLA may lead to off-target binding, triggering an exaggerated immune response to specific drugs. Certain genes associated with HLA are connected to severe reactions to medications. Variations in any genes affecting these three determinants of drug response can impact the outcomes of treatment.