Ever since DNA was first confirmed as the genetic material, researchers have been wondering whether it might be altered as a kind of intervention against disease. Now, 50 years later, the human genome is defined, the specific genetic cause of several diseases defined, methods of transferring genetic material are known and clinical trials have been started.
This development has raised great expectations and the hope of treatment of many diseases by gene therapy. However, gene therapy means changing the genetic constitution, which has raised concern and an ethical debate. In many countries governments set up special committees to consider this question.
In all cases the conclusion has been that gene therapy does not pose any new ethical dilemma so long as it is used to heal a clinical disease (rather than, for example, the alteration of some other attribute). The corrective DNA is introduced into specific cells of the body where the defect (mutation) is causing the disease. Any changes to a somatic cell are not transferred to the next generation, thus such somatic gene therapy is considered acceptable.
However, it is also possible to insert a gene into an early embryo, so it is introduced into the germline of the new individual. Because any gene inserted in the germline this way would be heritable by future generations, this type of gene therapy is not currently allowed. Examples of diseases where trials with gene therapy have been initiated are given in Table 1.