Directed introduction and expression of new genetic information in cells of an organism for therapeutic purposes. Only somatic gene therapy is presently permitted, and the introduction of genetic material into germ-line cells is not allowed.
The science of gene therapy has its beginnings in the early 1980s, subsequent to the identification of several disease-related genes and the development of technologies for gene isolation, purification and transfer to cells in culture. Many different human diseases represent theoretical targets for gene therapeutic intervention and the strategies developed depend on the nature of the disease to be treated. Table 1 illustrates several classes of human disease and the respective treatment strategies currently being followed. It goes without saying that detailed knowledge of the molecular mechanisms of disease development and progression is a prerequisite for the development of gene therapeutic intervention