Gene Therapy

Gene therapy involves the direct genetic modification of cells of the patient in order to achieve a therapeutic goal. There are two possible types of gene therapy interventions that can be performed on individuals. Such interventions can be performed on an individual's somatic cells (that is, any cell in an organism that is not a reproductive cell) or on the gamete or gamete forming cells, called germ line cells. This entry briefly reviews the ethical and social issues that have arisen in somatic gene therapy, while having a larger focus on the issues present in germ line gene therapy. Developments in gene therapy often appear in the news, but rarely do such accounts fully analyze these issues.

Somatic gene therapy has the potential to treat a wide range of disorders, including inherited conditions, cancers, and infectious diseases. In gene therapy, an exogenous genetic sequence, called a transgene, is introduced into human subjects with the aim of correcting phenotypic (expressed) or genotypic (inherited) abnormalities or to provide cells with new functions. To date, human gene therapy research has been focused almost exclusively on the modification of somatic cells because these genetic modifications only affect the individual patient. By contrast, direct germ line gene therapy is still in its infancy. Germ line gene therapy affects the germ line and therefore also the genome of future generations. Germ line gene therapy has been discussed as a means to treat mitochondrial diseases, that is, diseases due to DNA deviations in genes in the mitochondrial DNA, by ooplasmic transfer. Otherwise it is currently used in the creation of transgenic animals.

Somatic gene therapy currently lies in the uncertain gray area between novel research topic and therapeutic reality. The first decade of human gene therapy has so far demonstrated that there are no quick solutions to developing systems that are capable of delivering genetic material to the correct cells, in sufficient quantity to have a lasting therapeutic effect, without toxic side effects resulting from either the vector used to carry the genetic material or overexpression of the gene product. Further, the clinical efficacy and safety of somatic gene therapy remains disputed and no form of it is yet in routine use. Over years of professional discussion of somatic gene therapy, an ethical consensus has evolved that views somatic gene therapy as an extension of conventional medical interventions. The ethical issues associated with somatic gene therapy are the same as in other experimental treatment as it relates to clinical research, fundamentally. The ethical issues in this case are the risk-benefit ratio, the criteria for enrollment of patients, the informed consent process, conflicts of interest, and the fear of misuses.

However, most ethical and social critique of human gene therapy has focused on the problematic nature of germ line gene therapy, which has been deemed both controversial and technically distant. Objections to it often stem from ideas about what is natural and arguments against intentionally causing genetic changes in future generations. However, in recent years there has been a provocative precedent for germ line gene therapy, because there are now children who have three biological parents as a result of the medical intervention referred to as ooplasmic transfer.

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