Preimplantation Genetic Screening/Testing for Aneuploidy
Genetic testing in IVF, specifically Preimplantation Genetic Screening/testing for Aneuploidy (PGS/PGT-A), is a crucial process. It involves examining the chromosomes in embryo cells to determine their viability. Euploid embryos, with 46 intact chromosomes, have a high chance of leading to a successful pregnancy, even in older women. On the other hand, aneuploid embryos, with abnormal chromosome numbers, often result in IVF failures and miscarriages.
Understanding Aneuploidy and “Mosaicism”
Mistakes in the genetic makeup, often causing IVF (In Vitro Fertilization) failures, can happen when eggs or sperm are being formed. When this happens during maturation of the egg (meiosis), fertilization will inevitably lead to the embryo, having an irregular numerical chromosomal quota, and this is irreversible. However, sometimes, these errors occur after fertilization, during a process called mitosis. In such cases, some of the embryo cells will be chromosomal in normal, while others may be aneuploid period. Such embryos are referred to as being “ mosaic” and they have the ability to “auto correct” in the uterus, resulting and in normal pregnancies.
We can tell if these genetic issues are due to meiosis or mitosis thanks to advanced techniques like next-generation gene sequencing (NGS).
When we test embryos, we only look at a few of their cells. If we find some normal cells alongside abnormal ones, we can be quite sure it’s mosaicism. However, if all the cells we check are abnormal, it’s less likely to be mosaicism, but we can’t rule it out completely. There’s a chance that some of the cells we didn’t test might be normal, and the embryo could still be mosaic. Such a mosaic embryo, if placed in the uterus, might self-correct and develop into a healthy baby.
In simple terms, when we analyze a few cells from an embryo, we can usually diagnose mosaicism accurately. But if all cells we check are abnormal, while it is highly unlikely that the embryo is mosaic, it is not impossible.
Age Matters in Aneuploidy
The likelihood of aneuploid embryos being “mosaic” varies with a woman’s age. Older women have a higher percentage of aneuploid eggs. Thus. As age increases, the chances of an aneuploid embryo successfully self-correcting in the uterus decrease significantly. It’s essential for older women to understand this when undergoing IVF with PGS/PGT-A.
Testing and Pregnancy Monitoring
For patients transferring potentially mosaic embryos, it’s advisable to undergo chorionic villus sampling (CVS) or amniocentesis during pregnancy to check for aneuploid development. This allows informed decisions about pregnancy continuation.
When to Consider PGS/PGT-A
PGS/PGT-A embryo selection should be considered in specific circumstances:
- Women over 39 years old
- Diminished ovarian reserve (DOR), regardless of age
- Unexplained IVF failure
- Recurrent pregnancy loss (RPL)
- Cases requiring gender balancing
- Women with immunologic implantation dysfunction (IID)
- Couples with balanced chromosomal translocations
- Known or expected genetic abnormalities
B. PGS/PGT-A for Gender Selection and Family Balancing
The ethical debate surrounding gender selection exists. However, it’s justifiable when used to prevent serious gender-specific genetic disorders. PGS/PGT-A with NGS can reliably determine gender.
Freedom of Choice
Concerns about family balancing affecting population gender balance are unfounded. Most couples don’t prioritize gender selection. In the United States, where most couples don’t prioritize gender selection, freedom of choice should prevail. Gender selection can be offered in cases with medical indications, such as:
- Sex-linked genetic disorders
- Serious genetic disorders with gender specificity
- Family balancing for couples with children of one gender or none
C. Preimplantation Genetic Testing For Single Gene Defects
Preimplantation Genetic Testing for Single Gene Defects (PGT-M) is a valuable method to reduce the risk of passing on specific genetic conditions. Consider PGT-M in the following situations:
- Both partners are carriers of the same autosomal recessive condition
- Either partner has an autosomal dominant disorder
- One partner has a dominant X-linked condition
- A partner has a mutation linked to hereditary cancer
- A previous child or pregnancy had a single gene disorder
PGT-M tests are tailored to each family’s specific genetic situation. It can be performed for almost any single gene disorder if the familial mutation is identified, and family members are available for testing preparation.
Preimplantation Genetic Screening/testing for Aneuploidy (PGS/PGT-A) is a crucial process in IVF, offering invaluable insights into the genetic makeup of embryos. This genetic testing method has both pros and cons that patients should carefully consider when embarking on their IVF journey. For some patients, the decision to opt for postnatal genetic testing is influenced by factors such as the potential transfer of mosaic embryos. This approach allows for informed decisions about the continuation of pregnancy, ensuring the health and well-being of both the mother and the developing baby. Understanding the pros and cons of genetic testing in IVF is crucial for making well-informed choices tailored to individual circumstances and aspirations.
The cost of Preimplantation Genetic Testing (PGT) is a significant consideration in your IVF journey. It’s essential to note that the expenses associated with genetic testing can vary from patient to patient, depending on their unique circumstances and testing requirements. Understanding the financial aspect is a crucial step in unlocking the potential of genetic testing in IVF while tailoring the process to your individual needs. To make well-informed decisions, it’s advisable to discuss the pricing structure and options with your clinic.
In conclusion, genetic testing in IVF is a complex but valuable tool that can significantly increase the chances of a successful pregnancy. Patients must weigh the pros and cons, consider the cost, and make informed decisions based on their individual circumstances and genetic situations. Whether it’s PGS/PGT-A for aneuploidy or PGT-M for single gene defects, the goal is to unlock the full potential of genetic testing in IVF, ensuring healthy and successful pregnancies.
If you’re eager to embark on your IVF journey or have questions about genetic testing, Sher Fertility Solutions is here to guide you every step of the way. Contact us today to explore your personalized path to a successful pregnancy and fulfill your dreams of parenthood. Your future family starts here.