Gene+Therapy

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=__Gene Therapy__=

**__What is Gene Therapy?__**
Gene therapy is the application of genetic engineering to insert enhanced genes into an individual in order to remedy a disease or dysfunction caused by a genetic defect. Through gene therapy it is possible to work directly at the base of a disorder rather than use drugs to simply alleviate its symptoms.

In the early 1970s, scientists proposed "gene surgery" for treating inherited diseases caused by faulty genes. The idea was to take out the disease-causing gene and surgically implant a gene that functioned properly. Although sound in theory, scientists, at that time and today, lack the biological knowledge or technical expertise needed to perform such a precise surgery in the human body. However, in 1983, a group of scientists from Baylor College of Medicine in Houston, Texas, proposed that gene therapy could one day be a viable approach for treating Lesch-Nyhan disease, a rare neurological disorder. The scientists conducted experiments in which an enzyme-producing gene (a specific type of protein) for correcting the disease was injected into a group of cells for replication. The scientists theorized the cells could then be injected into people with Lesch-Nyhan disease, thus correcting the genetic defect that caused the disease.

As the science of genetics advanced throughout the 1980s, gene therapy gained an established foothold in the minds of medical scientists as a promising approach to treatments for specific diseases.

**__Types of Gene Therapy__**
There are two types of gene therapy: Germ line gene therapy and Somatic gene therapy.
 * //Germ line// gene therapy is when germ cells, such as sperm or eggs, are modified by the introduction of functional genes. These functional genes are integrated into their genomes, therefore the change would be heritable and could be passed on to later generations.
 * //Somatic// gene therapy is when therapeutic genes are transferred into the somatic cells of a patient, meaning any modifications and effects would be restricted to the individual and not heritable.

**__Methods and Approaches__**
There are several approahces to go about gene therapy.
 * A normal gene may be inserted into a nonspecific location within the genome to replace a nonfunctional gene. This approach is most common.
 * An abnormal gene could be exchanged for a normal gene through homologous recombination.
 * The abnormal gene could be repaired through selective reverse mutation, which returns the gene to its normal function.
 * The regulation (the degree to which a gene is turned on or off) of a particular gene could be altered.

__**The Pros and Cons**__
Some of the controversies of gene therapy include:
 * //Short-lived nature of gene therapy// – Before gene therapy can become a permanent cure for any condition, the therapeutic DNA introduced into target cells must remain functional and the cells containing the therapeutic DNA must be long-lived and stable. Problems with integrating therapeutic DNA into the genome and the rapidly dividing nature of many cells prevent gene therapy from achieving any long-term benefits. Patients will have to undergo multiple rounds of gene therapy.
 * //Immune response// – Any time a foreign object is introduced into human tissues, the immune system has evolved to attack the invader. The risk of stimulating the immune system in a way that reduces gene therapy effectiveness is always a possibility. Furthermore, the immune system's enhanced response to invaders that it has seen before makes it difficult for gene therapy to be repeated in patients.
 * //Chance of inducing a tumor (insertional mutagenesis)// -- If the DNA is integrated in the wrong place in the genome, for example in a tumor suppressor gene, it could induce a tumor. This has occurred in clinical trials for X-linked severe combined immunodeficiency (X-SCID) patients, in which hematopoietic stem cells were transduced with a corrective transgene using a retrovirus, and this led to the development of T cell leukemia in 3 of 20 patients.
 * //Ethical issues// -- Many religious beliefs are in opposition to any sort of science in the study for human modification. Gene therapy seems to be one of several "hot button" issues concerning what is politically acceptable.

On the other hand, there are also conveniences to gene therapy. Gene therapy could be a solution for curing genetic diseases and abnomalities. With further scientific development, gene therapy may be ultimately able to quell current genetic diseases such as heart disease, high blood pressure, Alzheimer's disease, arthritis, and diabetes.

__**Bibliography**__
Category. "What Is Gene Therapy? Information About Gene Therapy." //Rare Diseases - Information About Rare Diseases//. N.p., n.d. Web. 29 Nov. 2009. .

"Gene Therapy." //Oak Ridge National Laboratory//. N.p., n.d. Web. 29 Nov. 2009. . "- Genetics & Public Policy Center || Science || Genetic Modification -." //- Genetics & Public Policy Center -//. N.p., n.d. Web. 29 Nov. 2009. .

Hogarth, Eric. "ASPECTS OF GENE THERAPY ." //NDSU - North Dakota State University//. N.p., n.d. Web. 29 Nov. 2009. .

Mauron, Alex. "Ethical aspects of gene therapy." //Geneva Foundation for Medical Education and Research//. N.p., 4 Sept. 2008. Web. 29 Nov. 2009. <http://www.gfmer.ch/Endo/Lectures