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.
- 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?
- 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?