Gene therapy is used to treat large number of diseases.
Research in the field of human gene therapy is directed towards correcting genetic defects of somatic cells i.e., cells that do not contribute to the next generation.
Human germ line therapy is not tried due to ethical, safety and technical reasons.
In human somatic cell gene therapy the fully functional and expressible gene is inserted into a target cell, by which that a specific genetic disease can be corrected permanently.
The development of a therapeutic agent for human passes through four levels of study and testing:
1. Pre clinical trials that include extensive invitro experiments and
research on laboratory animals.
2. Phase I trials with a small number (6 to 10) of human
subjects.
3. Phase II trials with an increased number of human
subjects to examine the effect of the drug or therapy.
4. Phase III trial includes a large human sample and fully
comphrensive analysis of the safety and efficacy of
the products.
