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Gene therapy is the treatment of a genetic disease where the gene that is absent or defective is replaced by a healthy gene.
A carrier molecule, called a vector carries the healthy gene to the target cell. The vector molecule is usually a viral vector that can easily follow the path to the target cell. The abnormal or unhealthy gene is then taken out and replaced by a normal, healthy gene. The virus is engineered so that it cannot reproduce and carries the human DNA to the targeted area.
Gene therapy cures genetic disorders and alters genes that couldn't originally carry out normal functions. Gene therapy has been most successful in curing genetic disorders that are only caused by a mutation in a single gene such as immune deficiency, cystic fibrosis, Canavan's disease, and Gaucher's disease. In the future scientists hope to use gene therapy to cure cancer, AIDS, Parkinson’s, Alzheimer’s, Lou Gehrig's disease, cardiovascular disease and arthritis.
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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 swapped 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.
In most gene therapy studies, a "normal" gene is inserted into the genome to replace an "abnormal," disease-causing gene. A carrier molecule called a vector must be used to deliver the therapeutic gene to the patient's target cells. Currently, the most common vector is a virus that has been genetically altered to carry normal human DNA. Viruses have evolved a way of encapsulating and delivering their genes to human cells in a pathogenic manner. Scientists have tried to take advantage of this capability and manipulate the virus genome to remove disease-causing genes and insert therapeutic genes. Target cells such as the patient's liver or lung cells are infected with the viral vector. The vector then unloads its genetic material containing the therapeutic human gene into the target cell. The generation of a functional protein product from the therapeutic gene restores the target cell to a normal state.
Some of the different types of viruses used as gene therapy vectors:
The most active research being done in gene therapy for children has been for genetic disorders such as cystic fibrosis. Other gene therapy trials involve children with severe immunodeficiencies, such as adenosine deaminase (ADA) deficiency (a rare genetic disease that makes children prone to serious infection), and those with familial hypercholesterolemia (extremely high levels of serum cholesterol). Future References: To cure genetic diseases, scientists must first determine which gene or set of genes causes each disease. The Human Genome Project and other international efforts have recently completed the initial work of sequencing and mapping virtually all of the 25,000 to 35,000 genes in the human cell. This research will provide new strategies to diagnose, treat, cure, and possibly prevent human diseases. Although this information will help scientists determine the genetic basis of many diseases, it will be a long time before diseases actually can be treated through gene therapy. "The Human Genome Project is just a start," Nicholson says. "It's going to locate genes for us, but it's not going to tell us what these genes do. That will be the next step. Once we have that information, we'll be able to take advantage of that knowledge to provide treatment and/or cures. “Gene therapy's potential to revolutionize medicine in the future is exciting, and its expectations for curing and preventing childhood diseases are encouraging. One day it may be possible to treat an unborn child for a genetic disease even before symptoms appear. Scientists are hoping the mapping of the human genome will lead the way toward cures for many diseases and that the successes of current clinical trials will create new opportunities and challenges. For now, however, it's a wait-and-see situation, calling for cautious optimism.
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Gene therapy is the biological technology of insertion genes into an indivivual cell to treat hereditary diseases such as Huntington's diseases, muscular dystrophy and even common diseases such as diabetes and vision impairment.
There are two kinds gene therapy. First, envivo is the process of gene fixation in the lab environment before being transferred into the somatic cells or body cells. In constrast, invivo is the process of fixing genes directly in body cells. The molecular biologists research about the disease and the gene that can be transferred into cells to determine what set of chromosomes will fix the problem. Then biologists put " the good gene" that they have fabricated onto the carrier gene. After that, the carrier gene is inserted and takes the new functioning gene to the site of the problem. Through mitosis, the repaired gene is aligned with the rest of the genes and incorportaed into the genome, taking the place of the malfunctioning gene. Therefore, the illness is cured and all of the genes work properly.
Gene therapy provides hope in treating diseases in the future. For example,
doctors hope to be able to treat HIV, AIDS, cancer, and Alzheimers disese. It is
a very recent discovery and new medicine, but it has the prospective to improve
the life of many people who before, had no chance of survival.
A doctor is transferring brain cell to treat a patient's brain tumor
Human Genome Project Information
European Society of Gene Therapy