Types of Gene Therapy,Germ Line GeneTherapy,Somatic Cell Gene Therapy,Germ Cells,Augmentation Gene Therapy,Targetted Gene

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	Types of Gene Therapy - Gene therapy may be classified into two types: (i) germ line gene therapy and (ii) somatic cell gene therapy. In case of germline gene therapy, germ cells, i.e., sperms or eggs (even zygotes), are modified by the introduction of functional genes, which are ordinarily integrated into their genomes. Therefore, the change due to therapy is heritable and passed on to later generations.
This approach, theoretically, is highly effective in counteracting the genetic disorders. But, this option is not considered, at least for the present, for application in human beings for a variety of technical and ethical reasons. In somatic cell gene therapy the gene is introduced only in somatic cells, especially of those tissues in which expression of the concerned gene is critical for health. Expression of the introduced gene relieves/eliminates symptoms of the disorder, but this effect is not heritable as it does not involve the germline.
Somatic cell therapy is the only feasible option, and clinical trials have already started mostly for the treatment of cancer and blood disorders. This approach is divided into two groups on the basis of the end result of the process: (i) addition or augmentation gene therapy and (ii) targetted gene transfer.