Preimplantation genetic testing
People should keep in mind that genetic testing isn’t a process that’s only offered to people undergoing IVF or other infertility treatments. Even for couples that conceive naturally, genetic screening is usually available. The process is strongly recommended for pregnant women over age 35 as the risk for chromosomal abnormalities can increase with age. Preimplantation genetic testing is slightly different because the process happens before the embryo transfer stage during an IVF cycle.
PGD vs PGS
There are 2 types of PGT available. Preimplantation genetic diagnosis (PGD) and preimplantation genetic screening (PGS) can both be performed before embryo transfer and focus on different concerns. PGD is better for people that are known carriers of genetic disorders. For example, people with a known family history of rare diseases like Huntington’s disease (HD) or Cystic Fibrosis (CF) would benefit from PGD testing. In this instance, the test will focus solely on identifying whether or not the known condition is present in the embryo. By contrast, PGS is more similar to prenatal genetic testing during pregnancy. The process screens for chromosomal abnormalities such as Down syndrome.
When PGT occurs
Preimplantation genetic testing can be combined with assisted hatching. Typically, just before fertilization, a lab technician cracks the egg’s exterior to help sperm enter the egg. After fertilization, the embryo changes into a blastocyst. During this stage, cells will be biopsied from the shell for genetic analysis. Once the results are received, the healthiest embryo can be transferred to the uterus for implantation. The total timeline can typically increase by an extra 7-10 days because of the added testing.
Most IVF participants are encouraged to undergo PGT. However, if any member of the couple has a family history of a known rare disease or is a carrier of a genetic condition that could be passed to the baby, PDG will be strongly encouraged. Additionally, IVF participants who have experienced multiple miscarriages can benefit from PGT and PGD testing.
The power of genetics
People need to remember that genetics isn’t a factor that fertility treatments can control. If an individual or both members of an IVF couple carry genes for rare or life-threatening diseases, genetic testing can only determine whether the resulting embryo will have those genes. However, opting for such testing gives a couple the chance to make an informed decision about proceeding with embryo transfer.