PGD And PGS: To Test Or Not To Test?
PGD, preimplantation genetic diagnosis, is the process of removing a cell from an in vitro fertilization embryo for genetic testing before transferring the embryo to the uterus.
PGD, preimplantation genetic diagnosis, tests for specific genetic conditions (cystic fibrosis, for example).
PGS, preimplantation genetic screening, is the proper term for testing for overall chromosomal normalcy in embryos. PGS is not looking for a specific disease diagnosis – it is screening the embryo for normal chromosome copy number.
With Ukrainian surrogacy, you will have the option to conduct PGD testing.
The Testing Process
A couple/few cells are removed from the embryos, which are about five days developed and safely frozen.
The DNA of the cells is then evaluated to determine if a problematic gene is present in each embryo. This process takes at least one full week.
Once PGD has identified embryos free of genetic problems, the embryo(s) will be placed in the surrogate’s uterus via IVF.
Any additional embryos that are free of genetic irregularities may be frozen for possible use in the future, while embryos with the problematic gene(s) are destroyed.
PGD can test for more than 100 different genetic conditions.
PGD helps reduce the chances of conceiving a child with a genetic disorder. This is especially important if the parent genetically related to the child is a:
- Carrier of sex-linked genetic disorders including Fragile X syndrome and Duchenne Muscular Dystrophy.
- Carrier of single gene disorders including cystic fibrosis and sickle cell anemia.
- Carrier of chromosomal translocations.
- Woman age 35 and over. (If a Ukrainian egg donor is used this will not be a consideration as all donors will be younger.)
The risk of a chromosomal abnormality in a live birth for a 25-year-old is 1/476.
If you wish to choose the gender of your child.
PGD is sophisticated, it must be done by highly experienced experts. Poor testing may disturb or traumatize the embryos, especially if done on day 3. Hence the experience of the procedure will provide more accurate results.
Embryo testing may be inconclusive, and it is thought some may repair themselves. This could lead to the disposing of viable embryos.
PGD cannot completely eliminate the risk of conceiving a child with a genetic disorder. In some cases, further testing is needed during pregnancy to ascertain if a genetic factor is still possible.
Although genetically present, some diseases only generate symptoms when carriers reach middle age. The probability of the development of such conditions should be a topic of discussion with your healthcare provider.
PGD does not replace the recommendation for prenatal testing.
As the American Society for Reproductive Medicine (ASRM) states, “Genetic screening may help identify couples who have an increased risk of age-related or familial genetic disorders and birth defects. No single test, however, can accurately predict the risk of all defects in a child, and many birth defects, such as those related to environmental and toxic exposures and those that are random and unexplained, are not genetically based and may not be detected with genetic screening.”
Just to make you aware, they are changing the names of PGD and PGS. They will now both be subcategories of PGT, Preimplantation Genetic Testing.