Targeted gene correction strategies.

We are now approaching the reality of success in gene therapy as our knowledge of the genetic basis of disease continues to grow, coupled with improved delivery methods for therapeutic nucleic acid molecules. It is apparent that gene therapy can be divided into two specific and very different approaches in which gene replacement, or augmentation, is differentiated from gene repair. In fact, gene augmentation is characterized by the delivery of the coding sequence of the gene of interest in an expression cassette. In contrast, gene repair differs in that the process targets for correction of the mutation responsible for the genetic disorder. The in situ repair of a gene has many advantages over conventional replacement methods. This review will concentrate on the various strategies currently available for gene repair. The potential benefits of correction versus augmentation will be addressed and possible future developments outlined.