Check out this essay by Emilie R. Bergeson from 1997 detailing the early thoughts on gene therapy and the moral dillema it represents. The author does a very good job of outlining how gene therapy can work, in vivo vs in vitro, and characterizing the first gene therapy experiments. Its interesting to read this article with the knowledge of some of the failures in gene therapy since 1997.
The author raises questions that the first scientists to get gene therapy approved to test on human patients including "why is the given disease a good candidate for gene therapy, what makes the scientists sure that the new gene will be properly inserted and regulated so as to be expressed usefully in the patient, and what are the technical details of the DNA and vector to be used."
The article also raises common ethical questions including wheter or not gene therapy should be used without genetic illness (meaning just to improve on a childs natural abilities). These experiments also bring up the ethical question of patent rights. Can anyone patent an organism, or patent the changes in a child as a result of gene therapy.
Overall I found the essay very informative.