Thursday, January 04, 2007

Shaping Babies

The number of genetic tests that can be performed during in vitro fertilization is skyrocketing. What does this mean for human reproduction?

By Emily Singer

Parents undergoing in vitro fertilization can now choose embryos based on their genetic risk of cancer and Alzheimer's. That's thanks to pre-implantation genetic diagnosis (PGD): genetic testing carried out after in vitro fertilization but before a fetus is returned to its mother's womb. The number of testing options is rapidly growing as scientists discover genetic variants linked to myriad health problems, including cancer, heart disease, and diabetes.

The surge in the number of potential tests brings the ethical quandaries associated with PGD back to the forefront. Currently, no laws exist in the United States governing the use of PGD. So doctors, clinicians, and their ethical-review boards are called on to make complex ethical decisions, such as if parents can choose the sex of their baby for nonmedical reasons or be allowed to screen embryos for diseases that they may never develop or that may only strike late in life.

Vardit Ravitsky, a bioethicist at the University of Pennsylvania, studies the ethical issues surrounding PGD. She says that the regulatory situation in the United States needs to change and outlines her view for Technology Review.

Technology Review: PGD has been plagued with ethical concerns since its creation more than a decade ago. What are we using PGD for now, and what are some of the ethical issues that arise?

Vardit Ravitsky: There is a spectrum of PGD tests that starts with strict medical use--PGD for single-gene diseases that strike early in life and are fatal, like Tay-Sachs. The sense in the bioethics community is that these uses are very appropriate--using a new technology for the ultimate medical goal of preventing suffering.

Further in the spectrum is the use of PGD for late-onset disease or for genes that increase risk of a disease. Here, the ethical issues become more complex. Some people feel this is absolutely inappropriate use. My sense from talking to clinicians is that they would be reluctant to screen or select against embryos that carry genes that increase risk because we don't know enough at this point. They argue that if we cross that line when we know so little, we are engaging in eugenic activities.

Bioethicists seem to have less objection to this use. They often emphasize parental autonomy, the right to choose what they want for their children.

TR: In the United States, who decides which tests are acceptable?

VR: At the end of the day, today in this country, the clinics are the gatekeepers. If you have cash and can find a clinic to provide the service, you can get it, whether it's a test for Huntington's disease or sex selection.

TR: Do we need more regulation?

VR: Few papers in the medical literature say the U.S. situation is really too open, but we do need to regulate at least some aspects of human reproduction. In the United Kingdom, one central body regulates everything involving reproduction and human embryos. Many people in the U.S. think we should try to adopt some elements of this system. But in a big and diverse country like the U.S., it's not feasible to adopt the full approach. We have religious controversy over embryos and a notion of reproductive freedom that is probably the strongest in the world.