Gene therapy is method in which nucleic bases are involved to treat human diseases. Gene therapy involves the delivery of altered genes into the body to replace damaged and missing genes. It is used as therapeutic drug by delivering into the diseased body. It has been around for quite some time, and now it is making its way to clinical trials. Gene therapy is considering as one of the advancement of genetic engineering. In future it will help scientists to insert therapeutic genes to treat genetic disorders without using drugs and surgeries. Although it has a promising future, it still remains risky and many researches are ongoing to make it more effective and safe. These includes approaches like treating or knocking out a mutated …show more content…
To treat such disease or make the mutated gene functional, a normal gene is inserted into the body to replace the mutated gene. There are any problems to have a successful gene therapy. For this the condition of the disease, the gene that cause the disease must be understood well and a normal working gene of the same function has to be available. When a gene that is placed directly into the body doesn’t function by its own, therefore a genetically engineered carries for the gene are constructed which are called vectors (4). Vectors are small pieces of DNA that can accept, carry and replicate other pieces of DNA. Properties of good vector includes: size, origin of replication, multiple cloning site and selectable marker genes (antibiotic resistance enzymes). There are many different kinds of vectors such as plasmid vectors, bacteriophage vectors, cosmid vectors, bacterial artificial chromosomes (BAC), Yeast artificial chromosomes (YAC) and shuttle vector. Each is selected by the size and type of DNA to be cloned. Among all these vectors the most promising vector is virus vectors. Due to genetic engineering scientists are using harmless viruses to deliver genes into the cells. Viruses are modified by removing their own DNA (genes) and replacing them with normal human genes. Since viruses have their own natural …show more content…
However, with the development of recombinant DNA technology, genes were modified and was thought that these modified genes can correct the defective genes disorders and many diseases phenotypes in mammals in vitro (6). Back in 1985 few scientists demonstrated that genes of ADA (adenosine deaminase) deficiency can be altered in tissue culture and then can be delivered into the body by retroviruses. By 1988 scientists were already transferring correct genes into the white blood cells of bone marrow animals with success. In 1989, scientists gave it a try of using gene therapy in cancer of TIL (tumor infiltration lymphocytes cells) for this, they created a viral vector and delivered altered TIL cells into the body with success. This experiment allowed scientists to confirm that gene therapy was effective as well as engineered viral vector was safe for humans. In 1990 scientists used gene therapy on few teenagers with ADA deficiency, by delivering modified corrected genes into the bodies of these patients with success and since over the past decade much progress has been done in the field of gene therapy.