Gene therapy is a new and as yet largely experimental branch of medicine that incorporates techniques of genetic engineering to correct inherited disorders or in-born errors of metabolism. The idea of curing a genetic disorder by repairing or replacing a faulty gene or gene product (protein) first occurred to Dr. W. French Anderson now recognized as the father of gene therapy.
In gene therapy the flawed gene is identified and copies of 
its normal version are produced in the laboratory by cloning. Then suitable host cells are selected from the patient’s body and genetic engineering is used to transfer copies of the normal version of the gene into it. The doctored cells are then returned to the body by injection. The introduced genes are incorporated into the chromosomes of the patient’s cells and propagate with each cell division. Since the introduced genes work normally and produce the protein that was previously either absent or malformed, the error is corrected in the victim who gets cured of the symptom. However, since gene therapy is not approved for genetic manipulation of the germ or reproductive cells, the cure cannot be passed onto future generations of the cured victims.