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Basic Principles and Approaches in Gene Therapy
Genes are specific sequences of bases that encode instructions on how to make proteins. Genes are carried on chromosomes and are the basic physical and functional units of heredity. Gene therapy is a technique for correcting defective genes responsible for disease development.
Researchers may use one of several approaches for correcting faulty genes:
1. Inserting a normal gene into a nonspecific location within the genome to replace a nonfunctional gene.
2. An abnormal gene could be swapped for a normal gene through homologous recombination; this approach is the most common.
3. The abnormal gene could be repaired through selective reverse mutation, which returns the gene to its normal function.
4. The regulation (the degree to which a gene is turned on or off) of a particular gene could be altered.
Gene Transfer Techniques
Gene therapy works by delivering the therapeutic gene to the patients’ target cells through the carrier molecule called a vector. Currently, the most common vector is a virus that has been genetically altered to carry normal human DNA. Once the vector enters target cells it unloads its genetic material containing the therapeutic human gene. The generation of a functional protein product from the therapeutic gene restores the target cell to a normal state.
The clinical application of gene transfer can be accomplished in either two ways: in vivo or ex vivo. During in vivo gene transfer the foreign gene is injected into the patient by viral and nonviral methods.
In contrast an ex vivo gene transfer involves a foreign gene transduced into the cells of a tissue biopsy, outside the body, and then resulting genetically modified cells are transplanted back into patient.
Limitations of Gene Therapy
The following are limiting factors on the use of gene therapy:
1. Short-lived nature of gene therapy.
2. Immune response of the patient.
3. Problems with viral vectors like patient-toxicity, immune and inflammatory responses, and gene control and targeting issues.
4. Limitation of sufficient quantity of the engineered gene that can be delivered.
5. Extreme cost.
6. Ethical restrictions.
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| Author: Vidya 23 May 2008 | Member Level: Diamond Points : 2 |
useful information
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| Author: Shyni 31 May 2008 | Member Level: Gold Points : 2 |
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| Author: helpu 31 May 2008 | Member Level: Gold Points : 0 |
Very Nice Article.This is very good.
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