Types of gene therapy

Germ line gene therapy
In the case of germ line gene therapy, germ cells, i.e., sperm or eggs, are modified by the introduction of functional genes, which are ordinarily integrated into their genomes. Therefore, the change due to therapy would be heritable and would be passed on to later generations. This new approach, theoretically, should be highly effective in counteracting genetic disorders. However, this option is prohibited for application in human beings, at least for the present, for a variety of technical and ethical reasons.

Somatic cell gene therapy
In somatic cell gene therapy, the gene is introduced only in somatic cells, especially of these 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 germ line. At present, somatic cell therapy is the only feasible option, and clinical trials addressing a variety of conditions have already begun