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What is pharmacogenomics and why is it considered the future of medicine?

People who have negative reactions to some medications are becoming more and more common. What does DNA have to do with this situation? What is science doing to counter this reality?.

Pharmaceutical products in containers of different colors

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LatinAmerican Post | Christopher Ramírez

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Leer en español: ¿Qué es la farmacogenómica y por qué se considera el futuro de la medicina?

According to the Mayo Clinic, a drug allergy can be defined as “an abnormal reaction of the immune system to that drug. All medications, whether over-the-counter or herbal prescriptions, can cause allergies. However, there are certain medications that are more likely to cause allergy.”

Likewise, the important medical center explains that this reaction is different from the so-called side effects mentioned in the medicine's own label, since the allergy can bring with it a toxicity that can even cause death.

However, there are other "contraindications" specific to each body with some medications that, although they cannot be considered an allergy, do generate complex effects on the genome, that is, the genetic code or DNA of the person who consumes them.

According to a 2003 study carried out by the International Genome Project, it was possible to detect that the DNA sequence between human beings is identical in at least 99.9%; however, it is in that 0.1% of diversity where the difference between one or another person is found, and that makes it unique before the others. Of course, it is also responsible for a patient reacting differently to one drug relative to another.

Thus, while in some patients certain medications are completely ineffective, in others they can cause unknown reactions that can be fatal. To avoid this, science created a procedure known as a pharmacogenomic test, with which to detect, on account of the DNA study, and determine if it will have a negative reaction to a biological before recommending it minimally.

This was explained by the British Pharmacological Society and the Royal College of Physicians, through a report published on March 24. According to the scientific document, to date it has been possible to find the genetic cause for the reaction contrary to that desired in more than 40 medications.

“Pharmacogenomic testing can be used to find out what gene variants an individual carries and whether they respond to the drugs they are given. This information can be used to guide medication and dosage choice, increasing the likelihood that each person will receive the most effective medication for them, at the best dosage.

This greatly reduces the chances that, in the first case, a medication will be administered whose reaction will not be satisfactory, since the patient's DNA does not have the necessary resources to adopt the benefits in their body. Or in a much more “catastrophic” scenario, the biological shock with the person's genome that causes an extremely dangerous chain reaction, not only for the treatment that is being carried out, but for the person himself.

To better understand this point, the Mayo Clinic describes a clear example related to the enzyme thiopurine methyltransferase (TPMT) and thiopurine drugs. To begin with, the report from the medical center explains that this medicine is used especially in the therapy of patients with autoimmune disorders such as Crohn's disease (which affects the digestive system), as well as some types of cancer, among which childhood leukemia stands out.

In this specific case, if a person's genome doesn't have enough TPMT, their body simply won't break down thiopurine drugs, which over time will lead to an extreme concentration that, among other effects, could damage bone marrow.

“Genetic testing can identify whether people are deficient in TPMT so their doctors can take steps to reduce the risk of serious side effects, either by prescribing lower-than-usual doses of thiopurine drugs or by using other drugs instead,” indicates the Mayo document.

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Genetics as the future of medicine

Of course, pharmacogenomic tests can be considered as the future of medicine; although some already consider it as the present. During the last decades, medical science has focused on the study of the human genome as a response to the way in which a body may or may not function to specific health treatments.

However, this type of demonstration is not simple, so parallel to the research related to the keys that a person's genome can offer to understand their health problems, there is another group of scientists who are looking for ways to find strategies much faster to find those keys.

In short, while some show the efficiency of genetics for diagnosing diseases, they look for tools that allow studying the genome in less time and thus come up with opinions in shorter periods of time.

An example of this is a report from the Garvan Institute of Medical Research in Sydney, published in the journal 'Science Advances' , in which the discovery of a test that allows a series of at least 50 genetic neurological diseases and neuromuscular disorders that were previously undetectable for years.

"We correctly diagnose all patients with known diseases, such as Huntington's disease, fragile X syndrome, hereditary cerebellar ataxias, myotonic dystrophies, myoclonic epilepsies and motor neuron diseases, among others," he said. Dr. Ira Deveson, director of genomic technologies at the Garvan Institute and lead author of the study.

In this way, medical science is using DNA as the main source of communication to learn first-hand what is happening in the human body, and thus avoid stumbles and errors with treatments that in the past claimed hundreds of lives.