Preimplantation Genetic testing is a medical procedure performed during in vitro fertilisation (IVF) to screen embryos for genetic abnormalities before they are transferred to the uterus.
Preimplantation Genetic Testing is a group of genetic tests that are performed on the embryos. This testing helps to ensure embryos without a specific genetic condition or chromosomal abnormalities, increasing the chances of a successful pregnancy and reducing the risk of passing on inherited genetic disorders.
Fertility specialists perform these tests for two specific reasons, which are the abnormalities in embryos, resulting in frequently failed implantation, miscarriage, and unsuccessful IVF.
- PGT-A (Preimplantation Genetic Testing for Aneuploidy): PGT-A identifies embryos with chromosomal abnormalities—aneuploidy—and helps to reduce the chance of miscarriage or chromosomal conditions, such as Down syndrome.
The purpose of PGT-A is to detect embryos with an abnormal number of chromosomes, or aneuploidy.
Use Case: Advanced maternal age, recurrent miscarriages, and unexplained infertility.
Goal: To increase the chances of chromosomal normalcy in embryos, reducing miscarriage risk and increasing the chance of a healthy pregnancy.
- PGT-M (Preimplantation Genetic Testing for Monogenic Disorders): This approach allows for the screening of genetic disorders caused by mutations in single genes; examples include cystic fibrosis, sickle-cell disease, and Tay-Sachs disease.
The purpose of PGT-M is screening embryos for specific genetic disorders caused by mutations in one gene.
Use Case: Couples that are carriers for single-gene disorders (e.g., cystic fibrosis, sickle cell disease, Huntington’s disease) or those with a family history of genetic conditions.
Goal: Prevent transmission of genetic conditions to offspring.
- PGT-SR (Preimplantation Genetic Testing for Structural Rearrangements): Tests for chromosomal structural abnormalities, such as translocations or inversions, that can impact embryo viability and development.
The purpose of PGT-SR is to identify embryos with structural abnormalities in chromosomes, such as:
Translocations (exchange of chromosome segments). Breakage and reunification of segments in an inverted orientation. Different associations are recommended in cases where established abnormalities are somehow in play.
The history of miscarriages or failed cycles in IVF is known as chromosomal rearrangements.
Who Should Consider PGT (Preimplantation Genetic Testing)?
1. Couples with Known Genetic Disorders
- Couples have known carrier status for specific genetic mutations or disorders such as cystic fibrosis or sickle cell anemia. PGT-M could help in avoiding transmission of these conditions to the baby.
2. Couples Who Have Miscarriages Repeatedly
- Chromosomal abnormalities in embryos are the common causes of recurrent pregnancy loss. PGT-A can identify healthy embryos to diminish the risk of miscarriage.
3. Older Women Undergoing IVF
- Women older than 35 years are documented to have higher chances of chromosomal abnormalities in their eggs. PGT-A could increase the chances of pregnancy success in older women.
4. Couples That Have Other Failed Cycles of IVF
- It identifies viable embryos for those with several failed IVF cycles, thus defining the biological problems.
5. Individuals with Known Chromosomal Rearrangements
- Couples where one partner has structural chromosomal abnormalities such as translocations or inversions could benefit from PGT-SR, which ensures selection of embryos with balanced chromosomes.
6. Couples Planning for a Single Embryo Transfer (SET)
- For families that want to minimize complications with multiple pregnancies, PGT will identify the healthiest single embryo for transfer.
7. Parents Concerned About Sex-Linked Disorders
- Some genetic conditions show linkage to specific chromosomes (e.g., hemophilia and Duchenne muscular dystrophy). PGT can identify embryos that do not carry sex-linked disorders.
8. Families with Existing Children Affected by Genetic Conditions
- Couples with one child already suffering from a genetic disorder might consider PGT to avoid the occurrence again.
The Process of PGT (Preimplantation Genetic Testing)
1. Ovarian Stimulation and Egg Retrieval
- The process begins with the woman receiving ovarian stimulation. Hormonal medications will be used to stimulate the ovaries and develop multiple eggs.
- The eggs are then collected through a minimally invasive surgical procedure called follicular aspiration.
2. In Vitro Fertilisation (IVF)
- The eggs that have been retrieved from the woman will undergo fertilization with sperm in the lab to produce embryos.
- Fertilization can either be natural, as in IVF, or ICSI, where a single sperm is injected into the egg.
3. Development of the Embryo
- Fertilized eggs are cultured in a laboratory for 5-7 days to promote development into embryos.
- Embryos would typically reach the blastocyst stage, which is the ideal stage for biopsy.
4. Embryo Biopsy
- A few cells from the outer layer of the embryo, also known as the trophoblast, are carefully extracted during the blastocyst stage. Such a procedure rarely compromises the embryo’s capacity for implantation and subsequent development.
5. Genetic Analysis
The biopsied cells are sent off for genetic testing. Based on the specific type of PGT, the analysis will look for:
- Chromosomal abnormalities (PGT-A).
- Known genetic mutations (PGT-M).
- Structural rearrangements (PGT-SR).
6. Embryo Freezing (Cryopreservation)
- After the biopsy, each embryo is frozen (vitrified) to ensure that its quality is preserved until the test results are available.
7. Result Evaluation
- Results usually come out within a few days to a week.
8. Embryo Transfer
- The healthiest embryo(s) determined by the PGT will be chosen for transfer.
9. Pregnancy Tests and Monitoring
- Blood tests performed two weeks after the transfer will confirm whether or not the embryo has implanted. Regular monitoring will be done to ensure this healthy start to a regularly progressing pregnancy.
What are the benefits of PGT (preimplantation genetic testing)?
1. Higher Success Rate of IVF
PGT filters out healthy embryos that conform to the required chromosome complement. This increases the chances of a successful pregnancy.
2. Reduce the risk of genetic disorders
Genetic abnormalities and mutations known to exist cause inherited diseases. This guarantees that those particular embryos are not implanted.
3. Lower rate of miscarriage
Miscarriages occur due to chromosomal abnormalities of embryos. Thus, PGT minimizes this risk by testing for chromosomally viable embryos.
4. Better Outcomes for High-Risk Couples
As a result, healthier pregnancies for couples with a history of recurrent miscarriage or genetic disorders. PGT gives peace of mind for those with a known family history of genetic disease.
5. Supports Getting a Family Started
It helps families avoid passing destructive genetic condition chances down onto their children. It will grant an opportunity for making an informed decision about the embryo transfer.
6. Empowering in Older Couples
There is more chance of chromosomal abnormality in older women above 35. PGT therefore makes it extremely probable that viable embryos will be selected for transfer, thus attempting to enhance the outcomes for older parents.
7. Reduces Emotional and Financial Strain
The screening of healthy embryos works nicely in reducing the emotional toll that the failed cycles of IVF lose. While incredibly expensive, it can spare time and repeat IVF cycles at a later stage.
8. Allows Single-Gene Testing
PGT-M can be useful in identifying condition-free embryos among carrier couples who carry a certain mutation. Being able to have a happier family sooner on. Less suffering, less risk of a child dying from difficult and unpleasant diseases.
Limitations and Ethical Considerations of Preimplantation Genetic Testing (PGT)
Limitations of Preimplantation Genetic Testing (PGT)
1. Limited Scope of Testing
PGT is limited to specific genetic abnormalities or chromosomal defects. They do not test for all genetic disorders or future health risks.
2. Risk of Embryo Damage
Although rare, the biopsy may cause damage to the embryo, which in turn can lessen its viability for implantation.
3. False Results
Although very good, this type of test is not altogether without risk. A small chance exists for false positives or negatives.
4. Emotional and Physical Strain
Going through an emotional process, IVF and PGT can be exhausting on the body. The disappointment caused when viable embryos are not found could be very upsetting to couples.
5. Quality and Quality
Many embryos may be excluded as a result of the test, bringing the number of transferable embryos down.
6. Time Implications
PGT makes the process of IVF longer as embryos are biopsied, tested, and then frozen before implantation.
7. Ethics for Certain Cases
In some countries and/or areas, using this type of testing for non-medical reasons (i.e., sex selection) is restricted by law.
Conclusion
For more details, you can contact Origyn IVF for further assistance on PGT (Preimplantation Genetic Test) and for other treatments too. Check out our website, https://www.origynivf.com/ and learn about the most advanced treatment facilities at Origyn IVF in Delhi, NCR. Here, you’ll find expert care and advanced solutions to help with your fertility and reproductive health issues. We have a team dedicated to ensuring that you are treated with personalized care and with the best standard of service for your parenthood journey.
People also ask for:
Q1. Does PGT (Preimplantation Genetic Test) guarantee a healthy baby?
- While PGT significantly reduces the risk of genetic disorders, it cannot guarantee a completely healthy baby, as it does not test for all possible conditions.
Q2. Is PGT (Preimplantation Genetic Test) safe for embryos?
- Yes, PGT (Preimplantation Genetic Test) is generally safe. The biopsy process removes a few cells from the outer layer of the embryo without affecting its ability to develop.
Q3. What is the success rate of PGT (Preimplantation Genetic Test)?
- PGT improves IVF success rates by identifying viable embryos for transfer, reducing miscarriage risks, and increasing the likelihood of pregnancy.
Q4. Are there any risks associated with PGT (Preimplantation Genetic Test)?
- Risks are minimal but may include embryo damage during biopsy, increased cost, or the emotional burden of not having viable embryos for transfer.
Q5. Can PGT (Pre-Implantation Genetic) detect all genetic disorders?
- No, PGT only tests for conditions it is built for. It fails to detect certain rare or complicated conditions.
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About Dr. Rashmi Sharma:-
Dr. Rashmi Sharma is an IVF specialist Consultant Reproductive Medicine and Director Origyn Fertility & IVF New Delhi MBBS (BHU), MD(BHU), DNB, MNAMS, FICOG, Diploma IVF and reproductive Medicine (Kiel University, Germany) Web Editor, Indian Fertility Society (2024-26) Former HOD, IVF dept, Moolchand Hospital, Delhi (2009-13) and Max Hospital, Pitampura, Delhi (2013-17), Director, Origyn Fertility & IVF, which has 4 branches across Delhi.
Origyn IVF has been accredited for 1-year fellowship in IVF and reproductive medicine along with an MSc in Clinical Embryology under Amity University and IFS Collaboration. Recipient of the “C. S. Dawn Award” for best paper presentation on her work on IVF /ICSI with genital tuberculosis, at All India Congress Of Obstetrics and Gynecology (AICOG 2010) Recipient of “Hall of Fame – Best IVF specialist in India – North” at Economic Times – National Fertility Awards,2019 and 2023 & 2024.
Origyn IVF received “Best IVF center in North India” and “Most integrated team in IVF, India – North” at Economic Times – National Fertility Awards, 2019 & 2024 Recipient of “Best IFS Executive” at Fertivision – 2018, Kochi. Authored various chapters in infertility books of repute. Many national and international paper presentations and publications.
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