Genetic Fixes and Future Generations

CNN -- Scientists at the University of Florida recently reported success in permanently changing the genetic control of blood pressure in rats, using gene therapy.

This is not the first successful gene therapy in an animal, but it is the first time a specific and useful genetic change has been passed on to the animal's offspring and even to the animals in a third generation. This feat was achieved by performing the gene therapy not only on the cells of the adult but on the so-called germline (eggs and sperm).

This success signals the possibility of germline gene therapy in humans. But the incredible potential of permanently curing both present patients as well as their future children and grandchildren also brings significant new risks and questions. Who can consent for future individuals? What are the risks of creating unwanted changes in future generations? How should we decide which kinds of gene therapy are acceptable to be applied to the germline?

What's your opinion?

The goal of gene therapy is to cure disease or ailments by permanently repairing problems caused by flaws in our genes. For example, gene therapy could potentially be used to "fix" a genetic flaw that causes diabetes and remove the need for insulin injections by repairing the body's process for metabolizing sugar. There are two choices for the target of such therapies -- either to cure just the individual by targeting the defective cells in his or her body (such as in the pancreas for diabetes), or to also modify the genes in sperm or eggs so that the genetic defect is removed from that family's gene pool forever.

So part of the promise of germline gene therapy is the prospect of treating not only affected individuals but all their future descendants before they exist. Parents would no longer pass genetic disease on to their children and their children's children.

Whatever change is achieved through germline gene therapy is permanent, for good or for bad -- permanent not only for individual patients but a permanent change to the gene pool that will last as long as descendants continue to pass on their genes. That means that both the benefits and the risks of germline gene therapy are magnified, since a treatment's effects don't stop with the patient, as in other sorts of medicine, but continue on across generations. How sure must we be that the changes created by gene therapy won't be harmful -- especially to future people -- before using this new technology?

Does good enough for us mean good enough for our grandchildren?

Even if we can agree that germline gene therapy is a sufficiently safe and acceptable way to permanently cure genetic disease, how can we guarantee respect for the interests of all those who are affected by it? The basis for ethical medical decision-making is that patients give their informed consent -- especially when significant risk accompanies a treatment option. But how can consent be obtained from future people? Since that's impossible, under what conditions can people today make decisions for the people of tomorrow?

It turns out that we frequently confront this problem in other areas -- decisions about federal budget deficits affect the economic outlook of future generations; decisions about the use of natural resources today determine the state of the environment we leave for the future. We make judgments about these and other issues by weighing the current risks and benefits against those expected to occur in the future. Future effects are inevitably perceived as less valuable, both because they are off in the distance and because we can't truly foresee what the future will hold -- new breakthroughs may render current thinking obsolete.

When the health of future humans is at stake, however, such calculations seem insufficient. Changes to our genetic legacy offered by germline gene therapy demand higher standards of certainty and safety, because once we start, going back is not an option, and continuing forward may alter the future. The challenge, then, is to think not only for ourselves, but also about how our decisions will affect those who come after us.