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For many of us, when we first learned about biology in middle school under the alias of life science, we were introduced to the world of genetics. Within this fascinating world of genetics, we learned about Gregor Mendel, Punnett Squares, and various genetic disorders. For some reason, we were simply told that genetic disorders were just something that happened if your mom and dad had a gene or some kind of mutation and you were just kind of stuck with this unlucky outcome from the game of life with no cure. However, scientists have been working hard to discover new ways of dealing with genetic disorders using methods that we wouldn’t really think of.

One of those ways is gene therapy. Gene therapy is an experimental treatment that is used to insert genetic material into an individual’s cells (3). The injected genetic material contains the correct sequence of DNA to replace the mutated version. In doing so, the hope is that the body will express the correct genes and produce the correct proteins. In order to deliver the genes, scientists use carriers, also known as vectors, and are most commonly viruses. Now it seems somewhat questionable that scientists would use viruses, which are responsible for some of themost severe illnesses in the world, to try and treat genetic disorders; however, there is method to their madness.

The beauty and convenience of using viruses to inject genetic material into cells is that viruses naturally do just that. Viruses are masters at delivering genetic material into cells, hijacking the cells function, and consequently, multiplying their genetic material through the body’s own cell cycle (4). All scientists have to do is just make sure that they remove the harmful, disease-causing genetic material from the virus and insert the good, genetic-disorder fixing genes instead. Scientist also use viruses for their wide range in complexity and function.

There are multiple types of viral vectors that scientist can use and each of them have their pros and cons. The most common type of viral vectors that scientist use are retroviruses, adenoviruses, and the herpes simplex virus (6). Retroviruses can insert themselves permanently into the genetic material of cells, but can also insert new genetic material into the incorrect position and disrupt the synthesis of correct proteins (2).  Adenoviruses are very useful for delivering genetic material to dividing and non-dividing cells, but the immune system may eliminate cells “infected” by adenoviruses. The herpes simplex virus is useful when delivering large chunks of genetic material, but cannot be maintained through transgenic expression.

Now it seems that it isn’t worth using gene therapy to treat genetic disorders when it is a somewhat new treatment and the chances of the treatment not working is high due to the challenge of correctly inserting the genes, but there have been so many promising clinical trials that say otherwise. One is the use of adeno-associated virus serotype 5 to treat hemophilia, a genetic disorder where blood is unable to clot, that saw a nearly 100% decrease in bleeding episodes after receiving one gene therapy treatment in a 52 week period (5). Another study is using adeno-associated virus AAV2 to treat cystic fibrosis, a disorder where the body overproduces thick mucus that builds up in organs and decrease their function, and has made promising progress (1). These two studies are a just a few of the numerous out there using gene therapy to treat a wide range of diseases from diabetes to cancer using small viruses that we normally think are the source of our illnesses.

Hopefully, as more time progresses and scientist learn more about viral vectors and how to make them better equipped to treat genetic disorders, we will see a decrease in genetic disorder related deaths. Once that happens, I have no doubt that when kids in the future are taking life science in middle school, they won’t be told that genetic disorders are incurable and untreatable.


References

[1] Brown, Jennifer. “Making Progress toward Gene Therapy for Cystic Fibrosis.” Iowa Now, The University of Iowa, 29 Sept. 2016, now.uiowa.edu/2016/09/gene-therapy-cystic-fibrosis.

[2] “Gene Therapy Retrovirus Vectors Explained.” Gene Therapy Net.com, Gene Therapy Net, www.genetherapynet.com/viral-vector/retroviruses.html.

[3] “Gene Therapy Technology Explained.” Gene Therapy Net.com, Gene Therapy Net, www.genetherapynet.com/what-is-gene-therapy.html.

[4] “Gene Therapy Viral Vectors Explained.” Gene Therapy Net.com, Gene Therapy Net, www.genetherapynet.com/viral-vectors.html.

[5] Rangarajan, Savita, et al. “AAV5–Factor VIII Gene Transfer in Severe Hemophilia A | NEJM.” New England Journal of Medicine, Oxford University Press, www.nejm.org/doi/full/10.1056/NEJMoa1708483.

[6] Robbins , Paul D, and Steven C Ghivizzani. “Viral Vectors for Gene Therapy.” Egyptian Journal of Medical Human Genetics, Elsevier, 19 Mar. 1999, www.sciencedirect.com/science/article/pii/S0163725898000205.

 

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