Pre-implantation Genetic Diagnosis (PGD), Pre-implantation Genetic Screening (PGS), Pre-implantation Genetic Diagnosis-Aneuploidy Screening (PGD-AS)

The goal of fertility treatment is a not only for you to have a successful pregnancy but also to have a healthy child. There is a newer treatment option, Pre-implantation Genetic Diagnosis (PGD), as well as Pre-implantation Genetic Screening (PGS), that may improve your chances for successful pregnancy. ‘PGD’ is often loosely used to reference all pre-implantation genetic testing.

The IVF (in-vitro fertilization) procedure offers unique access to the oocyte (egg) and pre-implantation embryo, which allows for early tests to visualize the chromosomes or to determine whether an embryo contains an abnormal or a mutated gene. Advanced DNA manipulation techniques are used to determine genetic diagnoses in these very early human embryos, prior to their implantation in the uterus. PGD/PGS is a complement to prenatal diagnosis, where the fetus is tested at 10-12 weeks by chorionic villi sampling (CVS) or amniocentesis at 20 weeks, therefore possibly preventing the difficult decision of whether to continue the pregnancy. When PGD/PGS is performed, only “healthy” embryos will be implanted, decreasing the risk for miscarriage due to pre-determined known abnormalities as well as greatly decreasing the chance that a child will be born with known mutations or disorders.

PGD is used when one or both genetic parents carry a gene mutation or a “balanced chromosomal rearrangement,” and testing is performed to determine if the specific mutation or an “unbalanced chromosomal complement” has been passed on to the oocyte or embryo. PGS applies when the genetic parents are presumed to be chromosomally normal but would like their embryos to be screened for abnormal chromosomal make-up. PGD and PGS are options available not only to couples that have an infertility diagnosis, but to any couple concerned about passing on an inherited genetic mutation.

At Laurel Fertility Care, our Laboratory Director has extensive embryo micromanipulation and biopsy experience. We work with leading teams of molecular biologists who provide specific genetic counseling, evaluation and perform the DNA testing using rigorous standards to virtually eliminate the possibility of a misdiagnosis. However, the possibility that other abnormalities presenting later as a consequence of the procedure cannot be excluded. Patients considering IVF with PGD also should be informed that pregnancy rates may be lower than those achieved with IVF in age-matched patients when PGD is not performed. Pregnancy rates after PGD may be reduced because genetic testing will decrease the number of embryos suitable for transfer. Abnormal or affected embryos will be specifically excluded and others may yield inconclusive results, fail to develop, or have decreased viability due to the biopsy procedure itself. Despite the fact that several hundred babies have been born through this method worldwide, it is important that to understand this is still considered an experimental procedure and they will need to undergo prenatal genetic testing (amniocentesis or chorionic villus sampling) during pregnancy to ensure that a proper diagnosis has been made.