Human Gene Therapy :: Biology Biological Genetic Essays

Human Gene Therapy Ashanthi Desilva is now able to ride her bike in her suburban Cleveland neighborhood. She can play basketball with her friends or go fishing with her family. She is slightly inconvenienced by her weekly shot of the critical immune system enzyme: adenosine deaminase (ADA). Ashanthi was born with a faulty gene that results in the inability for her body to produce ADA, leaving her dangerously susceptible to even the weakest of infections (Brown). In 1990, researchers collected samples of Ashanthi's blood, isolated some of her white blood cells, and incorporated into them a virus engineered to contain a healthy ADA gene. These cells were then injected back into her body. She was the first patient to undergo gene therapy, and without that therapy and the weekly shots of ADA, she would have been destined for a life of isolation. Human gene therapy is the replacement of an absent or faulty gene with a functioning gene. As a result, the body is able to produce the correct enzyme or protein, thereby eliminating the cause of the disease (Gene_Therapy_Overview). There are essentially two types of gene therapy: somatic cell therapy and germ line therapy. Somatic cell therapy involves treating any cells of the individual, except the gametes, at the cellular level to correct an absent or malfunctioning gene. This can be accomplished in three ways: ex vivo, in situ, or in vivo. Ex vivo involves removing cells from the patient, altering the genetic material, and placing them back into the patient. In situ requires the vector be placed directly into the affected tissues. In vivo gene therapy involves injecting the vector into the bloodstream. The vector then must find the target tissue and deliver the therapeutic genes. Germ line gene therapy treats the gametes or an embryo, which would be used in the case of in vitro fertilization. The difference between somatic and germ line gene therapy may seem to be subtle; however, the alterations obtained through germ line therapy are not only found in that generation, but are passed on to the individuals progeny. That has serious repercussions when it comes to discussing the ethics of using germ line therapy. Presently, similar techniques are being examined for both somatic and germ line gene therapy, but germ line therapy is more difficult (Coults). This is not to say that somatic cell gene therapy is easily accomplished. One challenge facing researchers is finding a suitable vector that would safely and efficiently deliver the genetic payload into the patients' genome.