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The Human Genome and Era of Personalized Medicine

By February 9, 2017PGx in the News

When the first human genome was sequenced early in the 2000’s, there was great hope that personalized medicine would soon become a reality.  The reason for optimism was that as more people had their genomes sequenced, the more data scientists and researchers would have on individual gene variation. It soon became apparent that certain genetic variations are responsible for people’s varied response to prescribed medications. This entails that one patient may handle a specific dosage and frequency of a drug treatment plan appropriately, while another patient may metabolize the medication in a completely different way and suffer severe adverse reactions. These differences are based on each individual’s genetic makeup.  It is this variation that has led to the field of pharmacogenomics, or pharmacogenetics, as it is often called.


With advances in gene sequencing techniques in the past five years or more, there has been a tremendous increase in the number of genomes sequenced and studied.  One particularly fruitful area has been the study of variation among humans in drug metabolism genes.


Genes are made of DNA.  The DNA sequence of the genes, determines the composition of proteins and enzymes that do most of the work of the cell. Simply put, every unique DNA sequence specifies how that unique protein is made.


Every human has drug metabolism genes (made up of DNA) that encode specific enzymes (made up of protein) responsible for metabolism of particular drugs or group of drugs. Through sophisticated techniques, advanced genome-wide studies have allowed scientists to make connections from gene variations (genotype) to specific symptoms due to treatment with a particular drug (phenotype). A simple explanation of the genotype-phenotype relationship is eye color.  You may have brown eyes, so that means your genotype codes for brown eyes, while your phenotype is the observed result of the gene’s expression.


Why Pharmacogenetic Testing?

Pharmacogenetics concerns itself with the study of gene variation and its effect on phenotype. The goal is to prevent side effects – phenotypes – that are damaging or dangerous.  In the past, drugs were prescribed by a trial and error process. This method is effective to a certain extent, but it can be costly, patients may suffer adverse reactions…  The study of pharmacogenetics and the process of pharmacogenetic testing, will eventually eliminate the trial and error process of prescribing medicines.


Pharmacogenetics testing helps physicians strategically target patient care based on the patient’s genetic code and is ushering in a new era of personalized medicine.  In the future, the promise of pharmacogenetics is to test every individual for drug metabolism gene variations to prevent uncomfortable or harmful side effects so that medicines can be used with more precision. The goal of personalized medicine is to usher in a new era of precision medicine and to strategically target patient care based on the patient’s genetic code.  These advances will help bring patients medicines that are prescribed with a knowledge of how the patients react to the medications.









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