Gene Therapy – The History, Techniques And Drawbacks
Gene therapy is an experimental science that uses genes to treat or prevent genetic disorders. The therapeutic genes are delivered to the patient’s cells as a ‘drug’ in order to treat the disease, or repair the cause of the disease in the DNA.
This science was first developed in the ’70s, when scientists discovered ways in which they could manipulate some viral genetic sequences and also identify the mutations that cause genetic diseases. The first attempt at gene therapy in humans was done in 1980, and it was unsuccessful. Cline, the scientist at the helm of this experiment, claimed that one of the genes he inserted into his patient had become active, but there was no evidence to support this claim. The first treatment that ever produced a genetic change happened in 1993.
The process of DNA transfer requires a section of the gene which contains the instructions for the formation of protein to be packaged within a virus, or any other vector, which kind of acts like the mode of transport. Viruses usually multiply by inserting their genetic material into cells, and manipulate them to keep producing the viral proteins. Scientists therefore replace the virus’ genes with the therapeutic DNA, which then gets replicated just like them.
Gene therapy uses different techniques in order to treat diseases. The first is known as genetic augmentation therapy. This technique is used to treat diseases that are caused by a gene’s inability to produce a functional protein. DNA that contains the functional gene is added into the cell, and this new gene is what is expected to produce the necessary protein. This type of technique can only be used if the disease hasn’t already done irreversible damage to the body. Disorders like cystic fibrosis could be treated like this.
The other technique is gene augmentation therapy, where the diseases targeted are those that are caused by the abnormal activity of a gene. The introduced gene prevents the mutated gene from expressing itself by interference or inhibition. This type of technique is useful in eliminating cancer cells.
The third technique requires the therapeutic DNA to be inserted into diseased cells, and kills them by either poisoning or marking them with protein that gets them targeted by the body’s natural immune system. This method requires precaution in order to avoid killing normal healthy cells.
Gene therapy has faced a number of hurdles since its discovery. The first is that its effects don’t last long. The therapeutic DNA has to remain functional and it’s necessary for the container cells to remain stable. This is still not possible and patients usually need to undergo multiple treatments. Also, the body’s natural immune system is difficult to override, as it is designed to attack foreign objects introduced in the body. The therapy is therefore ineffective as the therapeutic DNA is registered as an ‘enemy’. Another drawback is that most genetic disorders are caused by multiple genes, thus making the treatment complicated. To add on to all these, the treatment is also expensive, and the genetic disorders that are currently treatable are very rare.