Locus control regions and gene therapy

Gene therapy is a procedure in which exogenous genetic material is introduced into the cells of a patient in order to correct an genetic error or to provide the cells of the patient with a new functional property. Correction can be achieved by gene targeting via homologous recombination, at present achieved with very low efficiency (reviewed in Yanez and Porter 1998), or by addition of a therapeutic gene (augmentation). For gene therapy to succeed in clinical practice, the therapeutic gene must be delivered efficiently into the appropriate cells (tissue) and, once delivered, the gene must be expressed at a therapeutical level. In this chapter (section A) I will summarise some of the efforts currently underway for the development of practical, efficient and safe methods for gene transfer in man and the rationale underlying these approaches as well as the limitations and the problems involved (Tables IA and IB). I will also address the following issues: regulation of gene expression (section B), possible targets for gene therapy (section C), creation of animal models for human diseases and their relevance to somatic gene therapy (section D) and ethical and social implications of gene therapy (section E).