Over the next few generations, the use of pre-implantation genetic diagnosis may become as common as amniocentesis, said David Adamson, a California-based reproductive endocrinologist and president-elect of the American Society for Reproductive Medicine.
PGD could allow scientists to screen out diseases that run in a family — such as breast cancer and Alzheimer's — to ensure a healthy embryo.
One bioethicist has coined a term for choosing the “best'' embryo — procreative beneficence — suggesting that if a couple has the ability to produce the healthiest child, they have a moral obligation to do so.
“This technology is going to determine how babies are born, and how we re-create ourselves,'' Adamson said.
While PGD was originally meant to avoid life-threatening hereditary childhood diseases, some parents are choosing embryos based on diseases that could develop much later in life, such as breast cancer.
Now PGD is also being used to avoid afflictions that are not fatal, such as an eye condition that could lead to blindness, said Mark Hughes, who does PGD testing at Genesis Genetics Institute in Detroit.
“No one understands these diseases better than the family who has it,'' he said.
“The family knows it's serious enough to go through such extraordinary approaches to avoid giving it to the next generation.''
While doctors such as Adamson and Hughes see the good in testing embryos for the avoidance of disease, others are chilled by what they see as potential abuse of the process.
They say that one day scientists may be able to pinpoint genes for such traits as hair colour and height.
The science may move from guaranteeing a healthy baby to customising the child.
“Will parents try to do that? Really select a child's characteristics the way you can pick the options on a car?'' asked Thomas Murray, president of The Hastings Centre in Garrison, New York, a research institute devoted to ethical issues in medicine and the life sciences.
“Not many. But it doesn't take many to make it an issue.''
Parents could end up engaging in “micro-eugenics'', said Stanford University physician and bioethicist William Hurlbut, a member of George W. Bush's President's Council on Bioethics.
Rather than a state-imposed programme of eugenics, it would be the parents who could weed out genes they consider undesirable, he said.
“Someone could easily make the argument that being short is like a disease because it may result in social disadvantages,'' Hurlbut said.
Such choices disturb ethicists such as Adrienne Asch at Yeshiva University, New York, who said parents should see children as worthwhile however they are, not as embryos to be selected into perfection.
Beyond family issues, some experts worry that as the science develops, insurance companies might move to require testing of embryos and, based on the results, deny the future child health or life insurance because that testing showed the child was likely to have heart disease or develop Alzheimer's.
Right now, there are no regulations or laws about how PGD can be used in the United States.
“Responsible physicians will not perform PGD for frivolous reasons,'' said Zev Rosenwaks, director of the Centre for Reproductive Medicine and Infertility at New York-Presbyterian/Weill Cornell Medical Centre in Manhattan.
“The theoretical applications of PGD are essentially in the science fiction realm. PGD is here to alleviate pain and suffering. If one follows that tenet, it is a relatively simple thing to follow.''
Contrarian view
Some experts, keeping an eye on PGD developments, such as Francis Fukuyama, a professor at the Johns Hopkins School of Advanced International Studies in Washington DC, call for an arm of government to oversee reproductive developments and breakthroughs.
“We need a mechanism for determining the moral acceptability of new biomedical technologies that really reflects an informed, democratic discussion,'' said Fukuyama, a former member of the President's Council on Bioethics.
“The scientists by themselves are not in a position to make those kinds of judgments.''
For Adamson, however, the future is not frightening. “I think we have to be confident in ourselves as a people and as a nation — that we will face these things.
"Let's weed the bad out as we come to it. We're not going to stop the future and we're not going to stop the technology.''
