[Gene therapy: technics, strategy and application].

The concept of gene therapy extends to all treatments involving modification of cellular genetics. This approach has numerous applications such as the treatment of genetic disorders, cancer and viral diseases. The first of these implies the introduction of a normal gene to replace the function of the defective gene. In the other two, several strategies may lead to a therapeutic effect. The transfer of genes is equally applicable in any disease where the expression of the gene in the particular tissue is more effective than systemic or local treatment with the corresponding protein (for example Dopamine or Tyrosine hydroxylase for Parkinson's Disease). According to its application and to the strategy chosen, therapeutic gene may be transferred, in vitro or in vivo, with the aid of plasmid vectors or recombinant viruses. These vectors may contain targeting systems and/or regulation of the specific expression of the target cell. Some encouraging results have been obtained for different applications in animals and there are numerous clinical studies currently in progress.