Genetic Diagnostic Tool Offers Hope for High Risk Couples Contemplating Pregnancy

Two recent studies show that preimplantation genetic diagnosis (PGD) is an effective diagnostic tool for women of advanced maternal age (over 38) and those in high-risk categories. The technique can be used to screen for dozens of genetically transmitted diseases with a high risk of transmission, as well as those that carry significant mortality and morbidity rates, such as cystic fibrosis, Tay Sachs disease, hemophilia, Fragile X syndrome, Barth's syndrome and Rett's syndrome.

PGD is a genetic testing tool that allows for the analysis and transfer of healthy embryos back to the uterus.

A single cell from an 8-cell embryo is removed and subjected to a number of DNA probes. Using PGD, reproductive scientists now can determine whether an embryo has extra or missing chromosomes, or aneuploidy.

Lawrence B. Werlin, founder and director of California-based Coastal Fertility Medical Center, presented his findings on the use of PGD at the annual American Society of Reproductive Medicine conference (ASRM).

The Genesis study looked at the chromosomal make-up of an embryo before implanting it into the uterus. Since in vitro fertilization (IVF) is an expensive, exacting procedure, the new study supports the use of PGD to select only those embryos with the highest likelihood for success.

Another study reconfirmed earlier findings that PGD helps facilitate successful pregnancy for women considered to be high-risk because they suffered from recurrent pregnancy loss, and/or were over age 38. This study found that approximately 75 percent of the embryos in the high-risk group had two or more chromosome abnormalities.

Since a vast percentage of first-trimester miscarriages occur due to chromosomal abnormality, PGD can help reduce the risk of miscarriage.

According to the March of Dimes, chromosomal and/or genetic anomalies are either solely (13%) or partially (up to 20%) to blame for up to one-third of the 150,000 babies born with a birth defect each year. What's more, chromosomal and genetic defects are on the rise, linked in part to such factors as advanced maternal and paternal age, family history, environmental toxins, infertility treatments and other unknown causes.

"PGD is a huge development in reproductive medicine," said Mark Leondires, lead reproductive endocrinologist with the Center for Advanced Reproductive Medicine in Norwalk Connecticut, commenting on the introduction of the procedure earlier this year.

"We finally have something to offer couples facing the heart-wrenching decision of wanting to have a baby on their own but at the same time being high risk for passing on a genetic defect. PGD offers the potential to significantly improve both the outcome of the pregnancy and the baby's chances for a normal, healthy life. It is very gratifying to be able to offer this kind of hope to patients struggling with questions of risks and fertility," added Dr. Leondires.