Recent advances in gene mapping and cloning coupled with improved mole
cular biology techniques have made gene therapy a potential therapeuti
c approach for numerous human diseases. This article describes the var
ious molecular biology principles that are involved in the design of t
herapeutic genes and the techniques used to deliver these genes to the
affected organ or tissue. Some examples of experimental studies and c
linical trials of gene therapy are provided. Finally, moral and ethica
l issues are discussed.