ABSTRACT

Gene therapy uses the transfer of nucleic acid to prevent disease.  It is now considered as a powerful therapeutic approach to a large number of genetically based and acquired human diseases such as cancer, acquired immunodeficiency syndrome (AIDS) and cystic fibrosis. The basic and molecular concepts of genetic diseases are discussed. The technology of gene therapy involves, vehicles for gene transfer and delivery, searching for the right target cells and the regulation of the gene expression i.e. getting the right gene into the right cells.

A number of vectors, viral and non-viral, are used for gene transfer. The viral vectors most commonly used are retroviruses, adenoviruses, adeno-associated viruses and herpes viruses. Each of these vectors has advantage and disadvantage. Each system for delivery has special features and the choice of vehicle is based upon a variety of factors including toxicity or immunogenecity of the viruses.  The non-viral gene therapy exhibits safety aspects. 

Gene transfer by the vectors applied in both ex-vivo and in-vivo way, which resulted in a promising success. A large number of genetic diseases were subjected to gene therapy. Focus in this review will be on general types of diseases such as the inherited diseases of the lung, the non-heritable diseases such as HIV and cancer. Many of these are now under thorough investigations in clinical trials.

In spite of the progress in gene therapy a number of major aspects need to have more basic research. These include improved types of vehicles, improved specificity of transfer or expression, generation of safer vectors, modulation of the host response against the virus, and the stability of gene expression.

Gene therapy raises a number of ethical issues especially on the germline gene therapy.