James Watson once said 'we think that our fate lies in our stars but the truth is that our fate lies in our gene.' This fate
that James Watson was taking about is contained in our gene and is a new
technique that has stirred the world of medical science. Gene Therapy.
Gene therapy as the name suggests is defined as the replacement of a
defective gene with a normal gene for the treatment of genetic diseases. However today this therapy can be used to treat a wide range of diseases. Gene therapy has an interesting history. Unlike most misconceptions this concept was imagined way back in 1960 when some biologists were working on sickle cell anemia. They found that this disorder was caused due to point mutation in beta-globin gene (responsible for the production of hemoglobin) resulting in glutamic acid being replaced by valine. These biologists imagined that sickle cell anemia could be cured by replacing the defective beta globin gene with a normal one. In 1970 scientists suggested that a defective gene could be replaced with a new one using 'gene surgery'. In 1983 scientists proposed that Lesh-Nyan syndrome (deficiency in purine synthesis) could be treated using gene therapy. Finally on 14th September 1990 history was created when scientist from National Institute of Health (NIH ),Maryland,USA cured a four year old girl suffering from SCID (severe complicated immunodeficiency) using gene therapy.
Depending on the type of cell the new gene is introduced into gene therapy is classified as Somatic gene therapy and Germ-line gene therapy. In
somatic gene therapy new gene is introduced in somatic cells. There are no heritable changes here as the correction is not passed to the progeny. This method however is not that effective having less chances of meeting success. In Germ-line gene therapy replacement of defective gene is done within a gamete forming tissue (germ cells). This can be used to cure sickle cell anameia or cystic fibrosis. But there are moral and ethical questions raised as a decision to use this therapy would not only affect a single individual but also his descendents.
Depending on the technique used gene therapy is of two types. In random or non-homologous recombination method the transfected DNA is introduced randomly in the genome. This technique has some serious disadvantages. The host chromosome gene might be under the control of regulatory sequence also the expression of the gene will depend on the site of its integration. It could be worse and this random integration can activate an oncogene resulting in cancer. The other technique involves Targeted or homologous recombination. In this there is site specific or targeted insertion of therapeutic replacement gene so that it exactly replaces the defective copy. This would definitely be a more preferred choice as there are more chances of the inserted sequence expressing itself. However it is very difficult to insert a gene in a specific position and for one gene correctly spliced more than thousand are inserted randomly. Thus gene therapy is in its nascent stage and will take years before it is perfected.
This therapy has many advantages; it can be used for the treatment of number of disorders like muscular dystrophy, sickle cell anaemia, cystic fibrosis,Huntington's disease etc. Different forms of cancer like that of lung and skin have been cured. This method has also found a place in treatment of HIV. Gene therapy has been revolutionizing the world of medicine and the focus has shifted from treatment of a disease to its prevention.
This therapy has some serious disadvantages like on 17th September 1999 Jesse Gelsinger an eighteen year old boy died as a result of his volunteering in an gene therapy experiment. This technology can find an application in the cosmetic industry as if scientist find the gene of youth/beauty, cosmetic surgery can be performed using gene therapy to stay young forever. Also this method can be used to control the genetic characters of offspring thus we can produce designer babies in the laboratory.
Gene therapy has some serious drawbacks and there must be specific guidelines on its use. All said and done gene therapy is in news more for good reasons than bad. But we can't deny that this will change the future of mankind. James Watson was thus right in saying that our fate lies definitely in our gene.