Process of Gene Therapy

The idea of gene therapy is a simple and logical  one, fix a faulty gene by replacing it with a healthy gene.   However, there are different approaches scientists take in order to do so.The Different Types of Gene therapy include:
1) Germ Line Gene Therapy
2)Somatic Cell Gene Therapy
3) Chimeraplasty

1) Germ Line Gene Therapy: This process involves the altering of a baby's the genome before it has even been born. The gene may be inserted through Germ line gene therapy is still an emerging technique that needs to be perfected before being tested on humans.  Germ line therapy is also, a  more challenging than the more common somatic cell gene therapy. However, germ line therapy  raises concerns regarding ethics and morality.
The two main methods of performing germ-line gene therapy would be:
  • To treat a pre-embryo that carries a serious genetic defect before implantation in the mother, with the use of in-vitro fertilization
  • To treat the germ cells (sperm or egg cells) of afflicted adults so that their genetic defects would not be passed on to offspring approach to delete the defective gene and insert a properly functioning replacement.

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2) Somatic Cell Gene Therapy:
  The most studied gene therapy, somatic cell therapy uses the insertion of a normal gene into the DNA of somatic cells in order to compensate for the non-functioning defective gene. Which can be done in a number of ways including: 
  • Inserting the gene into any location within the genome to replace a nonfunctional gene, which is the most commonly used
  • Switching the abnormal gene  for a normal gene through homologous recombination.
  • Fixing  through selective reverse mutation, which returns the gene to its normal function.
Somatic Gene therapy delivers the normal gene into a somatic or body cell of an individual. This allows for specific locations of the body to be targeted but also limits the inheritance of the correct genome to future generations.

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Virus Vectors:

Both Somatic and Germ line gene therapy,  need a way to insert DNA into a cell therefore carrier molecule called a vector must be used to deliver the therapeutic gene to the patient's target cells. The most efficient and effective vectors to date are viruses. Viruses can be genetically altered to carry normal human DNA, then passing on the healthy genes to human cells. Much like a chauffeur who picks up and delivers people to certain locations.  Some examples of viruses that are used as vectors are: Retroviruses, Retroviruses, Adeno-associated viruses, and Herpes simplex viruses.
 In Vivo Vs. Ex Vivo

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3) Chimeraplasty : This technique is the least known of all three methods. It is a non- viral method that is still being researched for its potential in gene therapy. Chimeraplasty is done by changing DNA sequences in a person's genome using a synthetic strand composed of RNA and DNA. This strand of RNA and DNA is known as a chimeraplast. The chimeraplast enters a cell and attaches itself to the target gene. The DNA of the chimeraplast and the cell complement each other except in the middle of the strand, where the chimeraplast's sequence is different from that of the cell. The DNA repair enzymes then replace the cells DNA with that of the chimeraplast. This leaves the chimeraplast's new sequence in the cell's DNA and the replaced DNA sequence then decays.                                                                                                                                                                                                                         

                                                                                                             Next:  Concerns and Controversy

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