Gene Therapy
Gene TherapyIn research facilities all around the world scientist are attempting to stop diseases at their very roots. Instead of trying to find drugs to cure illnesses they are trying to change the genes that cause the diseases. The process by which this is done is called gene therapy. Gene therapy is the deliberate alteration of the human genome for alleviation of disease. The studies of gene therapy began in the mid 1980's to early 1990's. The focus then was "treating diseases caused by such single-gene defects as hemophilia, Duchene's muscular dystrophy, and sickle-cell anemia."1 As time passed new technologies, techniques, strategies and ideas for transferring genes have been presented.
William French Anderson, Michael Blaise, and Ken Culver performed the first successful gene therapy on a human in 1990. They developed a protocol for treating Adenosine deaminase (ADA) deficiency, a severe combined immune deficiency, also known as the "Boy in the Bubble disease." ADA deficiency is a result of inheriting two copies of the defective ADA gene. Possession of a normal gene leads to the continuous, regular production of ADA in cells throughout the body. Without at least one properly functioning gene, children have no way of converting deoxyadenosine (a waste product) into inosine. This leads to the rapid build-up of deoxyadenosine in the system, which becomes phosphorlyzed into a toxic triphosphate, which kills T-cells. The result is an almost complete failure of the immune system and early death.
Previous treatment options included bone marrow transplants, which worked well with matched donors. A major breakthrough occurred with the development of polyethylene glycol coated ADA (PEG-ADA). This treatment introduces coated ADA into the blood stream, although not into the cells. It requires expensive, painful shots on a weekly basis, but it succeeded in giving children with ADA deficiency a new lease on life. While their immune systems were far from normal, PEG-ADA allows some semblance of a normal life and a much-increased life span.
The first patient to undergo federally approved gene therapy was a young girl named Ashanti DeSilva, in 1990. Ashanti's success immediately sparked a torrent of gene therapy investment and research.
There are two main types of gene therapy. There is somatic gene therapy, which encompasses all of the cells of the body excluding sperm and egg cells. The second type is germline gene therapy. The difference between the two is that changes made in somatic gene therapy are not passed on to offspring, whereas in germline gene therapy the changes are passed onto the next generation. Not much research is being done in germline gene therapy because of technical and ethical reasons.
The first step of gene therapy is to find the location of the problem gene or genes. DNA probes are used to find the problem DNA. "The technique relies upon the fact that complimentary pieces of DNA stick together."5 The Human Genome Project is...
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