ABSTRACT
In 1990, the first clinical trials of somatic gene therapy for inherited disease were started on two girls suffering from adenosine deaminase (ADA) deficiency. A number of characteristics have resulted in ADA deficiency becoming an attractive candidate for the initial clinical trials of gene therapy. The development of gene therapy for ADA deficiency has evolved through a natural succession of in vitro and in vivo models over a long period of time. The target cell initially selected for gene transfer was the HSC. The problems facing gene therapy for ADA deficiency mirror the problems facing gene therapy per se. The optimism generated by the first trials of gene therapy has now been tempered with a healthy dose of reality. These initial studies have met with varying degrees of success and no trial can claim to have achieved the objective of clinical cure.
