Gene therapy can be defined as the insertion of genetic material into cells for the treatment of disease. Although gene therapy was envisaged initially as a means of treating inherited genetic diseases, disciplines as diverse as oncology, cardiology, endocrinology, and infectious diseases are currently developing novel therapeutic strategies that have in common gene transfer into cells. Gene therapy naturally intends to supplement a defective mutant allele with a functional one. In most gene therapy studies, a normal gene is inserted into the genome to supplement an abnormal disease causing gene. To deliver the therapeutic gene to the patient’s target cells, a carrier called a vector have to be used. Currently, the most common vector is a virus that has been genetically altered to carry normal human DNA. The vector 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.
Types of Gene Therapy
Gene Therapy can be classified into two types: Somatic gene therapy and Germ line gene therapy.
- Somatic gene therapy : In this gene therapy, the therapeutic genes are moved into the somatic cells or body of a patient. Due to somatic gene therapy the modifications that occur will be restricted to the individual patient only. But these modifications will not be inherited by the patient’s offspring or later generations.
- Germ line gene therapy: In this type, germ cells such as sperm or eggs are modified by the introduction of genes which are in function and these functional genes are included into their genomes. In this type the modifications would be heritable to and passed on to later generations. But this type is highly controversial for a variety of technical and ethical reasons.
The gene therapy can be categorised into two types: in vivo therapy and ex vivo therapy. In the case of in vivo therapy the therapeutic genes are directly introduced in to the patient’s body and in ex vivo category the cells are removed from the patient and after manipulation they are returned to the patient .
