Chapter 40 : Bioethics Case Study: Gene Therapy

Abstract:

Leroy Walters, of Georgetown University’s Kennedy Institute of Bioethics, divided gene therapy into four possible categories. (1) Somatic-cell gene therapy for the cure or prevention of disease. Example: insertion of a DNA sequence into a person’s cells to allow production of an enzyme like adenosine deaminase. (2) Germ line gene therapy for cure or prevention of disease. Example: insertion of an adenosine deaminase sequence into early embryo or reproductive cells, which would affect not only the individual but all of his or her offspring. (3) Somatic-cell enhancement. Example: insertion of a DNA sequence to improve memory, increase height, or increase intelligence, which would affect only that individual. (4) Germ line enhancement. Example: insertion of a DNA sequence for enhancement into a blastocyst, sperm, or egg, which would affect future generations. Germ line therapy (altering disease genes so that the individual not only will be healthy but will pass on the healthy genes to his or her offspring) is considered desirable by some, but the techniques used to alter animal embryos have far too high a failure rate to consider their application to humans at this time. In the future, however, physicians will be able to detect many more defective genes than those that cause illnesses that are incurable and untreatable. Some genetic defects that are life threatening will be controllable with therapeutics (e.g., hemophilia). Other genetic defects will simply indicate a propensity to develop a disease.