written by: Jason C. Chavis•edited by: Paul Arnold•updated: 5/17/2010
Of all aspects of genetic research gene therapy has some of the greatest potential to cure diseases. Although the field is still in its infancy, the possibilities for gene therapy remain positive even despite concerns over the safety of test subjects.
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What is Gene Therapy?
Gene therapy uses genetic technology to insert specific genes into the cells and tissues of an individual. The general goal of the research and implementation is to treat diseases, especially hereditary defects. Functional genes are used to replace mutated or defective genes. Antisense technology is a form of modern gene therapy that has shown to have positive results.
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How Does Gene Therapy Work?
There are many different ways to target genes that can be used to make gene therapy work. The most common method is inserting a normal gene into a non-specific location within the genome with the goal of replacing a non-functional gene. Using homologous recombination, abnormal genes can be replaced with normal genes. Reverse mutation, such as that in antisense technology, can repair abnormal genes with a technique of selective reverse mutation. Also, using adjustments in enzyme levels which modify protein creation essentially turn a gene on or off.
Right: Gene therapy using an adenovirus vector. (Supplied by the National Institutes of Health; Wikimedia Commons; Public Domain; http://en.wikipedia.org/wiki/File:Gene_therapy.jpg)
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Why is Gene Therapy Difficult?
Gene therapy has proven very difficult for genetic scientists and engineers. Much of this stems from the nature of DNA and human immune response.
Due to the fact that most cells within the body can rapidly divide, successfully integrating gene therapy methods proves to be a short-lived option. In order for the therapeutic methods to be adopted by a cell, several rounds of gene therapy must take place to make the cell retain the information for a long period of time.
The human immune system can evolve to attack any invading bodies. This means that gene therapy can prove to be difficult since repeating the methods and programs in a cell or tissue can be met with evolving defense mechanisms.
The fact that much of the gene therapy used in modern cases must utilize viral vectors poses a number of potential problems to patients such as: toxicity levels and the possibility that the virus could evolve to attack other sections of a cell.
A number of human deaths have been associated to gene therapy research, commonly stemming from unseen side effects.
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What is Germ Line Gene Therapy?
Germ line gene therapy uses a concept in which the benefits of the modifications can be passed on through successive generations. This deals with the altering of sperm or eggs to remove or enhance a certain genetic trait. This has the potential of limiting the effects of genetic disorders in humans, however, research on humans has been limited by many ethical and technological concerns. It is illegal in most countries.
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Which Type of Illnesses Could Gene Therapy Cure?
A variety of illnesses and diseases could possibly be cured by gene therapy. Most scientists are presently focused on single-gene defects in human DNA that cause diseases such as cystic fibrosis, sickle cell anemia, muscular dystrophy and hemophilia. The overall potential of curing every genetic disorder thus far remains a possibility, but the dynamics of this technology have not been identified.