WHAT IS PGD/PGS FOR IVF?
PGD (Pre-Implantation Genetic Diagnosis) and PGS (Preimplantation Genetic Screening) are actually a number of procedures that combined have the ability to determine genetic information about an embryo before it is transferred back into the uterus. This information allows for decision making prior to embryo transfer so that abnormal embryos may be prevented from becoming ongoing intrauterine pregnancies. In this way, later decisions which are morally and ethically difficult and become necessary when a genetically abnormal pregnancy is detected by traditional testing such as Amniocentesis or Chorionic Villus Sampling (CVS) are eliminated.
HOW SHOULD WE USE PGD/PGS?
Now that we have this new technology, we have to determine when and how to use it. Since the development of CGH and with the move to blastocyst biopsy, we now believe that PGS has application to women over 30 years old in any IVF cycle. Our most recent data show that there is an increased pregnancy rate compared to cycles where PGS has not been performed in all age groups over 30. Significantly we are able to achieve these high pregnancy rates with the transfer of only one or two embryos.’ The data further suggests that we may see a higher embryo implantation rate when one embryo is transferred compared to two.” In addition,’ individuals who are known to have an abnormal genetic makeup of their own and women with recurrent miscarriages who have an otherwise normal evaluation will benefit from PGS.” Those who are carriers of a disease caused by a single gene disorder continue to benefit from the use of PGD.’ It is important to counsel the couples who are offered PGS that the risks of the procedure must be carefully weighed against the potential benefits before deciding to use it as part of their treatment.’ However,’ we have enough experience now that the risk to the embryo from the biopsy procedure is minimal.’ We believe now that PGS allows us to maximize the success of IVF and lower the incidence of multiple pregnancy by transferring only one or two genetically normal embryos.
However, as PGS becomes more widespread, there will become the possibility for its use in more debatable situations. As we learn more about the composition of the human genome and can determine which traits are determined by particular genes, the potential to design the makeup of an individual by removing or inserting genes becomes a possibility. This is an area that will become extremely complicated both ethically and morally. It is the responsibility of the medical community to insure that this technology is put to use in the most well thought out manner. These difficult issues will be the subjects of much debate in the years to come. It is safe to say, however, that the development of PGS is one of the most exciting and important milestones in the short history of Assisted Reproductive Technology.
READ HERE FOR MORE INFORMATION FROM DR. ANDERSON ABOUT PGS RESEARCH, THE FUTURE OF PGS AND ADVANCED MATERNAL AGE
Also visit ChromosomeScreening.org, an informative’resource for patients considering PGD/PGS.