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Gene Therapy - Case J1

Michael Walford is an immunologist and a clinical investigator who has done extensive work on amino deaminase (ADA) deficiency, a congenital condition stemming from a genetic defect that results in a highly impaired immune system. The disease leaves its victims subject to a multitude of potentially lethal infections and, consequently, babies born with this condition must be isolated in sterile chambers where they live out their lives.

Dr. Walford has developed gene therapy whereby the patient's bone marrow cells are extracted, exposed to a retrovirus that inserts the corrected DNA sequence, and then reintroduced into the patient. This procedure results in a permanent change in the genetic make-up of the patient's immune cell-producing tissues. The affected cells are "somatic" meaning they are not germ cells and, therefore, their genetic material is not transmitted to future generations.

Questions:

  1. Because only somatic cells are treated, the genetic defect causing the disease may still be passed on to future generations. This procedure, which is costly and not without risk, would have to be repeated on the patient's affected offspring, and all succeeding generations born with the disease. Should researchers focus instead on "germ cell" therapies -- that is to say, altering the genetic constitution of sperm or egg cells such that the correction will spare future generations of this disease?
  2. In this instance, germ cell therapy would alleviate suffering in generations of individuals. Would you feel differently about this procedure if it were designed to correct genetically caused deafness? What if the procedure were intended to correct a tendency toward obesity? Are certain applications of this procedure appropriate and others inappropriate?
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