gene therapy

n treatment directed to curing genetic disease by introducing normal genes into patients to overcome the effects of defective genes, using techniques of genetic engineering . The most radical approach would be to do this at a very early stage in the embryo, so that the new gene would be incorporated into the germ cells (ova and sperm) and would therefore be inheritable. However, this approach is not considered to be either safe or ethical, because the consequences would affect all descendants of the patient, and it is not being pursued. In somatic cell gene therapy the healthy gene is inserted into somatic cells (such as the haemopoietic stem cell of the bone marrow) that give rise to other cells. All the surviving descendants of these modified cells will then be normal and, if present in sufficient numbers, the condition will be cured (the defective gene will, however, still be present in the germ cells).