PGD & PGS: What Are They?
During your initial consultations you will be asked to consider and decide on any potential tests you’d like to have completed on your developing embryos. Most tests are performed after creation of the embryo and prior to their transfer into your surrogate’s uterus. These tests can highlight a number of things from sex of the fetus to presence of any potential genetic disorders.
Understanding the different types of tests available is a bit like eating a bowl of alphabet soup; they’re all abbreviated and occasionally medical professionals can forget that this may be your first experience to these tests. Perhaps the most often confused tests are the Pre-Implantation Genetic Diagnosis (PGD) and Pre-Implantation Genetic Screening (PGS). Both tests require a biopsy be completed on your embryo on day 5 or 6. Here’s a look at how these two very similar tests differ.
This test represents the more exhaustive screening option as it screens for specific diseases. This test is often recommended for couples with a family history of genetic diseases or the knowledge that at least one contributor is a carrier for specific diseases. The test is able to identify a battery of genetic diseases including:
- Cystic Fibrosis
- Huntington’s Disease
- Tay Sachs
- Muscular Dystrophy
- Sickle Cell Anemia
- Spinal Muscular Atrophy
- Muscular Dystrophy
- Marfan’s Syndrome
PGS looks specifically at chromosomal numbers. A typical, healthy embryo should have 46 pairs of chromosomes. This test will identify if there are fewer or greater chromosomes that what is considered ideal. Abnormalities in chromosomal numbers can lead to failure to implant, increased odds of miscarriage, and genetic disorders including Downs Syndrome. This test is recommended for those wanting to attempt only single embryo transfers as a way to aid in the selection of the best embryo for transfer.
Can We Do Both?
A commonly asked question is if your embryo is able to have both tests completed. The general answer is yes. In patients who carry a single gene mutation, it is not only possible but recommended.
Remember that if anyone you encounter during your experience begins to use jargon that is unfamiliar to you, it is perfectly acceptable to stop them and ask for clarification on terminology. These terms are foreign to most and you should not feel any hesitation to ask for explanation. Understanding your options will help you make the best choices possible for your growing family.