The Role of Gene Therapy in Future Disease Treatment

Abstract

Gene therapy is a relatively new form of treatment; one surrounding much criticism as to how effective it can be, as well as how unethical it can be. There is a large amount of people on either side of this debate, as well as those who are indifferent. This literature review, an understanding, will give insight into what gene therapy is; as well as talking about two diseases in which gene therapy was effective. These examinations of the case studies will show how much we can do, even with the vast limitations surrounding the treatment, and suggests that it is still a key element for the future in disease treatment.

A review and understanding

Over the past decade, the ideas and implications surrounding gene therapy have become more apparent. Throughout media, gene therapy has been regarded as a miraculous discovery, as well as being an ethical felony. The topic is highly debated amongst the populous, as well as there being a significant amount of those who only understand so much about it. With recent, research, and findings, gene therapy has advanced over the past decade; holding new promise for the present and future. This literature review will be going over the subject of gene therapy and its implications. In order to do this, the paper will be going over some key questions in elements to create an underlying on the subject, which are:

1. What is gene therapy?
2. Case Studies
3. Leber’s Congenital Amaurosis
4. Severe Combined Immunodeficiency (SCID)
5. Conclusions and Implications of gene therapy

Understanding each of these key elements, and ideas, highlights the complexity of gene therapy and what it is. The case studies will show an actual occurrence of what gene therapy has done for an individual, the severity of the diseases, and more specifically how it has helped them. These elements will help create an understanding of not just gene therapy as it is now, but what it could mean for the future of the human race, as well as what new things it could lead up to.

What Is Gene Therapy?

Gene therapy, as it is now, is an experimental medical technique that is used to treat or prevent diseases by using genes . When it comes to diseases genes are damaged, broken, or missing. Gene therapy helps diseased tissue and organs, in this case, in order for them to work properly; this is done by adding corrected copies of a bad gene that is causing the problem (What is Gene Therapy? n.d.). When it comes to fixing genes there are more than just replacing a mutated gene that caused the disease, others include: Stopping or deactivating the mutated gene that is not working properly, or introducing a new gene into the living organisms body so that it will be able to help fight a certain disease (Gene therapy, What is gene therapy? 2015).

The process. To get the genes into the organism carriers, called vectors , are used to deliver the gene as inserting the gene directly into a cell is ineffective (Gene therapy, How does gene therapy work? 2015). Vectors can be injected or given intravenously (IV for short) directly into the specific tissue containing the bad genes; the individual cells, in the tissue, then take in the new genes (Gene therapy, How does gene therapy work? 2015). Once the new genes are implemented, the information is then used to build corrected RNA and protein molecules; the molecules than do their job as they normally done in a healthy individual (What is gene therapy? n.d.).

Alternatively, a sample of cells can be removed from the patient where it can then be exposed to the vectors in a more contained setting like a laboratory (Gene Therapy, How does gene therapy work? 2015). Outside of the patient the sample cells will undergo the same process as described before, taking in the new genes, but this time the sample cell’s will be returned to the patient; if this form a treatment is successful, the new gene given by the vector will create the correct functioning protein (Gene Therapy, How does gene therapy work? 2015).

Vectors. Certain viruses can be used as vectors because they can effectively transfer the new gene, in varying degrees, by infecting the cell; however, the viruses are modified so that they cannot cause harm to the organism (Gene therapy, How does gene therapy work? 2015). There are two main types of viruses used as they provide certain key characteristics when transmitting the new genes, they’re retroviruses and adenoviruses (Gene therapy, How does gene therapy work? 2015). Retroviruses, when injected, integrate their genetic material into the chromosomes of the organism; effectively implanting the new genes with it (Gene therapy, How does gene therapy work? 2015). Adenoviruses on the other hand only introduce their DNA, along with the new genes, inside of the nucleus of the cell; leaving the chromosome as it is (Gene therapy, How does gene therapy work? 2015).

Case Studies

Gene therapy is still undergoing studies to determine the effectiveness of the treatment. Clinical trials, for those who participate, are being run and is regulated by The U.S. Food and Drug Administration (FDA) as they oversee all gene therapy products in the United states (Gene Therapy, Is gene therapy safe? 2015). Research on the effectiveness of gene therapy has already been run. It has, of now, shown us the effectiveness that gene therapy has on the treatment of diseases. We will now look at a two cases where gene therapy was effective and shows promise.

Leber’s Congenital Amaurosis (LCA). Those born with LCA begin to lose their vision as they get over and by the time they’re 40 they will be completely blind (Kaiser, 2009). There is one form of LCA, called LCA2, where those born with it have a defective gene called RPE65 that is responsible for helping the retina’s light-sensing cells make rhodopsin, which is a pigment needed to absorb light (Kaiser, 2009). The pigment plays a viable role because without it the photoreceptor cells gradually die, causing the blindness (Kaiser, 2009). In 2001, researchers at the University of Pennsylvania (Penn) were able to show that they could successfully restore partial vision in blind dogs by injecting good copies of the RPE65 gene into their eyes (Kaiser, 2009)

With the collaboration of the Penn team and the Children’s Hospital of Philadelphia, the team began a small safety study on the therapy of humans in 2007 (Kaiser, 2009). They began by injecting vectors carrying the RPE65 gene into each of the patient’s worse eye (Kaiser, 2009). In April of 2008, a similar study in the United Kingdom was published showing that four, of six young adults with LCA2, had improvements in the sensing of light and were able to perform better inside of an obstacle course (Kaiser, 2009). From earlier animal tests by the Penn team, they knew that the children should show better improvement as their retinal tissue are more intact than adults (Kaiser, 2009).

In 2009, the reports from their findings on their patients had shown that the children developed much more light sensitivity than the adults did, a fact of about 4 times as much; they also made far fewer mistakes in the obstacle course (Kaiser, 2009). In the case of Corey Haas, a patient who participated in the experiment, has told reporters that he can now recognize faces, read large print books, and ride a bicycle around his neighborhood without any help with the use of his treated eye (Kaiser, 2009).

Severe Combined Immunodeficiency (SCID). X-linked SCID is an inherited disorder of the immune system that occurs almost entirely in males, as the gene is located on the x chromosome (McGeady, 2012 and X-linked SCID, 2009). Mutations in the IL2RG gene are what cause X-linked SCID; the gene provides the instructions for making protein that, in turn, play a critical role for a normal immune system to function (X-linked SCID, 2009). Another form of SCID can be caused by the body’s deficiency to create an enzyme called adenosine deaminase (ADA), which is critical for lymphocytes to develop (McGeady, 2012). Those born with the disorder are prone to getting infections caused by certain fungi, bacteria, and viruses; the organisms that cause the infections do not ordinarily cause illness in healthy individuals (McGeady, 2012). However, because of the defect, those born with SCID experience slower growth, skin rashes, and chronic diarrhea that can all lead to death in the infancy stage (McGeady, 2012). X-linked SCID is the most prominent form of severe immunodeficiency, affecting at least 1 in 50,000 to 100,000 newborns (X-linked SCID, 2009).

More than 21 years ago, SCID was the first condition to be treated with gene therapy (Geddes, 2013). In subsequent trials at the time, four of the young patients were diagnosed with leukemia 2 years after receiving treatment (Geddes, 2013). Around this time, 1995, an 18-year old would die after receiving gene therapy because of the virus that was used to implant the corrected genes (Geddes, 2013).

In 2013, results from a preliminary test were presented to the European Society of Gene and Cell Therapy, stating that two children who received an improved SCID gene therapy have continued to show signs of improved immune systems (Geddes, 2013). Following these findings, three children have been treated since then and they are all showing signs of improved immune systems and may make a full recovery (Geddes, 2013). One of the three children is a girl named Nina, who in this case, has a ADA-SCID (Geddes, 2013). Bone marrow, from Nina, was taken and implanted with a working version of the ADA gene, before being placed back inside the body (Geddes, 2013). In April of 2013, Nina was only expected to show little signs of improvement by December of that year (Geddes, 2013). Come August of that year, four months before, Nina showed much improvement in her white blood cells as they had nearly doubled; today she lives and has a healthy immune system (Geddes, 2013).

Conclusions and Future Implications

Gene therapy is still new and continues to progress in the form of future treatment for diseases. The particular treatment is based upon DNA and it will still take time to completely understand, even small amounts of it, what certain parts do. It is still very much in the early stages as there continues to be controversy surrounding the treatment. In time this may go away as current and past research has shown what the treatment is able to do; even in its current state. The two case studies that I brought up are very serious and life threatening, of which gene therapy has shown us that there is promise in the future treatment of the disease. In Nina’s case, surrounding ADA-SCID, the treatment behind it has shown great promise for a very deadly disease that we could not previously fight nearly as effective as gene therapy. Further research still needs and has to be done but current studies show that it works, either a little or by a whole lot. The future of gene therapy will be filled with more research to show if it will or will not be the miraculous discovery we thought it was and even if that is the case, it will more than likely give rise to a new form of treatment we’ve yet to discover.