I received this article today about PGD.
PGD stands for Pre-Implantation Genetic Diagnosis, the procedure we used to find Sofia.
HEALTH BEAT: PRE-IMPLANTATION GENETIC DIAGNOSIS
Genetic test’s benefits and ethics debated
Imagine a procedure by which an inherited disorder — say, hemophilia — can be permanently eliminated from a family’s gene pool.
It’s not the stuff of science fiction; it’s called pre-implantation genetic diagnosis and has become a tool for fertility specialists.
“From my viewpoint, it’s broken the sound barrier of human reproduction,” said Dr. Joel Brasch, medical director and founder of Chicago IVF fertility clinic. “We’re now in control of our genetic pool.”
PGD is not without controversy, however; a recent article in the New England Journal of Medicine cast doubts on some of its benefits. Other specialists fired back a rebuttal to that article.
PGD is performed as part of in-vitro fertilization. In IVF, eggs are extracted from the female, then combined with the male’s sperm to create a human embryo, which is then transferred into the woman. By testing the embryo before implantation, Brasch said, doctors can spot genetic markers for cystic fibrosis, breast cancer, ovarian cancer, multiple types of leukemia and hemophilia. Down syndrome also is identifiable through PGD. And by using embryos without any of the markers, the diseases can be removed from a family’s gene pool.
There are 4,000 to 5,000 genetic markers right now, Brasch said, “and the list is growing monthly.”
Still, cautioned Dr. Eugene Pergament, a clinical professor in the Department of Obstetrics and Gynecology at Northwestern University’s Feinberg School of Medicine, recent studies are casting some doubt on the overall benefits of PGD.
“Conceptually it makes a lot of sense, to think you can literally reach in, remove a cell, genetically analyze it and enhance a pregnancy and pregnancy outcome,” he said. “But it’s turning out to be quite the opposite. It is not enhancing the pregnancy outcomes. It’s not even enhancing the pregnancy rates.”
That’s because PGD, which has been in use since 1990, is used not only to test for a rare inherited disease but also as a test for other chromosomal abnormalities, such as the cause of recurrent miscarriages, or for patients having IVF with advanced female age or patients of any age who have had repeated IVF failure.
“The controversy about PGD,” Pergament said, “I think a large part of it is the ethicacy of doing what we call aneuploid screening.” That involves looking at and eliminating embryos carrying an abnormal number of chromosomes, which is separate from screening for inherited conditions. “Aneuploid screening is a very popular approach, and that is controversial.”
He said studies in Belgium and the Netherlands have found that PGD is not effective, an idea that was repeated in the New England Journal of Medicine.
Despite the doubts, PGD is becoming more common. Worldwide, 2,000 to 3,000 PGD procedures were performed in 2000. That number today is thought to be between 5,000 and 10,000 a year, maybe even closer to 20,000. Definite numbers are difficult to come by because of the absence of a worldwide database.
Last year, a study conducted by Johns Hopkins University’s Center for Genetics and Public Policy, in cooperation with the Society for Assisted Reproductive Technology, found that 74 percent of the 186 in-vitro fertilization centers surveyed offered PGD services to their patients. The clinics reported doing approximately 3,000 PGD procedures in 2005, and authors of the study estimated that 4 percent to 6 percent of all in-vitro cycles included PGD.
Brasch emphasized that PGD is not cloning, gene manipulation or experimentation, which are against the law. It is merely gene identification, which is legal, and is an alternative to selective pregnancy termination.
He also realizes it generates debate.
“We are years, maybe decades, away from dealing with these technologies from a legal or ethical perspective,” Brasch said. “It’s fascinating, but the technology comes decades before the legal questions or ethical questions.”
