PGD and PGS: Why Genetic Counseling is a Prerequisite

Couples who are at risk of passing on an inherited disease are probably familiar with genetic counselors. However, those who have decided to undergo IVF with Preimplantation Genetic Diagnosis (PGD) will need to see a genetic counselor who is specialized in the procedure of PGD itself. It is important to make sure that the mutation in question can be diagnosed by PGD since not all heritable diseases have DNA probes. And sometimes there are other means of using PGD to determine mutation likelihood. In cases where there is concern about chromosomal abnormalities rather than single gene defects, Preimplantation Genetic Screening (PGS) is another option that requires a genetic counseling session. The genetic counselor can help patients understand the basics of chromosomes, how they affect the health of embryos and what this testing conveys about the embryos. Some of the common reasons why patients undergo PGS include: 1. Age (eggs of women >35 years old have a higher risk for chromosome abnormalities), 2. Unexplained recurrent pregnancy loss, 3. Gender selection for genetic disease, 4. History of unexplained unsuccessful IVF cycles. Who Are Genetic Counselors? Genetic counselors are health care professionals with graduate degree training in genetics and counseling, and certified by the American Board of Genetic Counseling. Genetic counselors practice in several subspecialty areas of genetics including assisted reproduction technologies, infertility genetics, and prenatal diagnosis. Because your genetic counselor can see you to discuss PGD or PGS, as well as prenatal testing options once you are pregnant, you will receive continuity of care. He/she will help you understand the complex information involved in your PGS cycle, and encourage your own decision making according to your needs. He/she will also serve as a liaison between you, your fertility doctors, and the PGD/PGS laboratory. What Happens During A Genetic Counseling Visit? There are two main objectives: 1. Family History Review: Your genetic counselor will take a three generation family tree (pedigree) to identify any additional genetic risks. This process ensures that the type of screening being offered is correct, and to identify any additional testing needed. Medical records may be requested for review. 2. Informed Consent: Informed consent includes an in depth discussion of the PGD/PGS process, from beginning to end, and a review of the information in the consent form, which is designed to inform and protect patients. Important information contained in the consent form includes risks and limitations of PGD/PGS, as well as the purpose of the procedure and the diagnostic technique. Your genetic counselor is available to answer questions regarding its content and to help you thoroughly understand it before signing. For those who have already gone through IVF, the beginning of the IVF with PGD/PGS cycle will be familiar. However, as complex as IVF is, embryo testing adds yet another layer of complexity. Additional steps include biopsy procedures, screening of a single cell for specific chromosome abnormalities or DNA mutations, and reviewing the results prior to embryo transfer. Only a genetic counselor is especially trained to mentally guide you through this process before you are actually in cycle so that, hopefully, there are no unanticipated outcomes. How Can I Find Out More? Please call 415-834-3095 to schedule a virtual consultation with a physician. -- Carolyn Givens, MD and Lauri Black, MS, CGC contributed to this article

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