Will Thai IVF Babies Get Genetic Diseases? PGT Screening and Genetic Disease Prevention Analysis
Opening: Real Consultation Scenario
A couple sat in the consultation room. The wife was 33, the husband 36, and they had been trying to conceive for 3 years without success. They were considering IVF in Thailand, but their biggest concern was not the success rate, but a more fundamental question: "Will Thai IVF babies get genetic diseases?"
The husband's family had a history of thalassemia carriage. Although the wife's screening was normal, the couple was particularly sensitive to genetic issues. This question actually points to the most central and easily misunderstood part of assisted reproductive technology—what embryo genetic testing can and cannot do.
Direct Answer: Will Thai IVF Babies Get Genetic Diseases?
This question needs to be answered in two scenarios.
Scenario 1: If third-generation IVF technology (PGT, Preimplantation Genetic Testing) is used, and the genetic problem of the couple or the embryo falls within the scope of PGT screening, then the risk of the Thai IVF baby developing a specific genetic disease can be significantly reduced, but it cannot achieve 100% exclusion of all genetic-related issues.
Scenario 2: If first or second-generation IVF (without PGT) is used, the probability of the baby having a genetic disease is basically the same as natural conception. IVF itself does not increase or decrease the risk of genetic diseases.
Therefore, the core difference lies in whether PGT technology is used and which genetic issues the PGT technology specifically screens for.
What Genetic Issues Can PGT Technology Screen For?
- PGT-A (Aneuploidy Screening): Detects whether the embryo's chromosome number is normal (e.g., Trisomy 21, Trisomy 18, Trisomy 13, sex chromosome abnormalities, etc.). This is a routine procedure currently carried out in most reproductive centers in Thailand.
- PGT-M (Monogenic Disease Screening): Targets known pathogenic gene mutations, such as thalassemia, cystic fibrosis, spinal muscular atrophy (SMA), hereditary deafness, etc. It requires first confirming the pathogenic gene loci of both partners.
- PGT-SR (Structural Rearrangement Screening): Detects whether the embryo has structural abnormalities such as balanced translocations, Robertsonian translocations, inversions, etc.
Many reproductive centers in Thailand have the technical capability for PGT-A and PGT-M. However, PGT-M requires custom probe design, takes longer, and demands higher laboratory standards.
Why Can IVF Babies Still Have Genetic Problems?
Even with PGT, it is still not possible to guarantee "zero genetic risk" for the embryo. The reasons behind this need to be understood from two perspectives: the sources of genetic diseases and the technical boundaries of PGT.
Three Sources of Genetic Diseases
- Parental Transmission: Pathogenic gene mutations carried by the parents are passed to the embryo. This is the scenario PGT-M can screen for.
- De Novo Mutations: Brand new gene mutations that occur during the formation of the embryo, not carried by either parent. PGT cannot predict de novo mutations because testing targets known loci.
- Mosaicism During Embryo Development: Some cells of the embryo are chromosomally normal, while others are abnormal. The cells obtained during biopsy may not represent the true status of the entire embryo.
Four Limitations of PGT Technology Itself
| Limitation Type | Specific Explanation | Impact on Genetic Risk |
|---|---|---|
| De Novo Mutations | PGT can only detect known pathogenic gene loci and cannot predict de novo mutations during embryo development. | A very small number of genetic diseases may be missed. |
| Mosaic Embryos | Biopsy takes 5-10 trophectoderm cells, which may not represent the entire embryo's genetic composition. | Possibility of false negatives. |
| Polygenic Diseases | Diseases like congenital heart disease, schizophrenia, type 2 diabetes, etc., are determined by multiple genes and the environment. PGT currently cannot screen for these. | Outside the scope of PGT screening. |
| Mitochondrial Diseases | Diseases caused by mitochondrial DNA mutations. PGT detection is difficult, and only a very few centers in Thailand can perform it. | Specific genetic diseases may be missed. |
Reproductive Doctor's Perspective: Understanding the Value and Boundaries of PGT
In clinical practice, I often encounter couples with two extreme expectations of PGT: one is that "if we do PGT, the baby will be absolutely healthy," and the other is that "PGT is useless because it can't find all the problems." Neither is accurate.
The value of PGT is that for couples who clearly carry pathogenic genes, or for those with recurrent miscarriages or embryonic chromosomal abnormalities, PGT can reduce the risk of transmitting genetic diseases from 25%-50% to less than 1%. However, PGT is a screening technology, not a diagnostic technology, and certainly not a guarantee for a "perfect baby."
The advantage of doing PGT in Thailand is the mature technology and many options. However, it is important to be aware that different laboratories vary in biopsy skills, testing platforms, and genetic counseling capabilities, which directly affects the reliability of the screening results.
When is it Suitable to Go to Thailand for PGT?
- One or both partners carry a clear pathogenic gene mutation (e.g., thalassemia, SMA, hemophilia, etc.)
- Recurrent spontaneous miscarriages or recurrent implantation failure suspected to be related to embryonic chromosomal abnormalities
- Female age ≥ 38 years, with an increased risk of embryonic aneuploidy
- One partner has a structural abnormality such as balanced translocation or Robertsonian translocation
- Previous history of giving birth to a child with a genetic disease
When is it Not Suitable?
- Doing PGT solely for "sex selection" (Some centers in Thailand may do it, but it is ethically controversial, and not all genetic diseases are sex-related).
- Without genetic counseling, unclear whether you carry pathogenic genes.
- Expecting PGT to guarantee the baby is "absolutely healthy" or "free from all genetic diseases."
- Very low ovarian reserve (e.g., AMH < 0.5 ng/mL), potentially unable to obtain enough embryos for PGT.
Actual Process of Thai IVF PGT Technology
From the decision to do PGT to the final transfer, the entire process usually takes 3-5 months, depending on the complexity of genetic counseling, the time for custom probe design, and embryo culture conditions.
Step 1: Pre-Genetic Counseling and Carrier Screening (1-2 months)
- Both partners undergo chromosomal karyotype analysis to rule out structural abnormalities.
- Genetic testing for known family genetic diseases to identify pathogenic loci.
- If there is no clear genetic history, expanded carrier screening (testing hundreds of recessive diseases at once) can be chosen to help discover unknown carrier risks.
- A genetic counselor assesses the risk of transmitting genetic diseases and formulates the PGT strategy.
Step 2: Embryo Culture and Biopsy (Approximately 2 weeks)
- The woman undergoes ovarian stimulation and egg retrieval; the man provides sperm; embryos are formed.
- Embryos are cultured until Day 5-6 to form blastocysts. At this stage, cells differentiate into the trophectoderm (future placenta) and the inner cell mass (future fetus).
- 5-10 cells are removed from the trophectoderm for genetic testing, and the embryo itself is cryopreserved.
Step 3: Genetic Testing (2-4 weeks)
- PGT-A uses NGS (Next-Generation Sequencing) or aCGH (Comparative Genomic Hybridization) technology to analyze chromosome numbers.
- PGT-M requires custom probes based on the pathogenic loci to analyze whether the embryo carries the pathogenic gene.
- Test results are categorized as: Euploid (normal chromosomes), Aneuploid (abnormal), Mosaic (some cells abnormal).
Step 4: Selection of Transferable Embryos and Transfer
- Priority is given to transferring embryos that are chromosomally normal and do not carry the pathogenic gene.
- Mosaic embryos require evaluation of the mosaicism ratio and type; some low-level mosaic embryos may still be considered for transfer.
- Pregnancy test is done 12-14 days after transfer.
The Most Easily Overlooked Details: Four Major Limitations of PGT
The following four points are often overlooked in clinical consultations but are crucial for decision-making.
1. De Novo Mutations Cannot Be Predicted
PGT-M requires knowing "which gene and which locus to check." If the embryo develops a completely new pathogenic mutation that never appeared in the parents' genetic reports, PGT-M cannot identify it. This situation is rare but does exist.
2. The Dilemma of Judging Mosaic Embryos
The biopsy takes trophectoderm cells, which will form the placenta; the fetus originates from the inner cell mass. The genetic composition of the trophectoderm and the fetus may be inconsistent (i.e., placental mosaicism or fetal mosaicism). This means: an embryo reported as "normal" by PGT still has a very low probability of chromosomal abnormalities in the fetus; conversely, an embryo reported as "mosaic" could still result in a normal fetus.
3. Polygenic Diseases Cannot Be Screened For Now
Common chronic diseases (such as hypertension, diabetes, schizophrenia, autism, etc.) are polygenic, determined by multiple genes and environmental factors. PGT can currently only screen for monogenic diseases and chromosomal abnormalities; it is powerless against polygenic diseases.
4. The Special Challenge of Mitochondrial Diseases
Mitochondrial DNA is entirely provided by the egg. If the mother carries a mitochondrial gene mutation, all offspring may be affected. The technical difficulty of detecting mitochondrial mutations via PGT is high. Only a very few laboratories in Thailand have this capability, and the accuracy needs further verification.
Interpretation of Test Indicators: Which Indicators Suggest Genetic Risk?
Before undergoing Thai IVF, the following tests can help assess genetic risk and determine the need for PGT.
| Test Item | Normal Reference | Abnormal Indication | Impact on PGT Decision |
|---|---|---|---|
| Chromosomal Karyotype Analysis | 46,XX or 46,XY | Balanced translocation, Robertsonian translocation, inversion, sex chromosome abnormality | Strongly recommend PGT-SR |
| Thalassemia Genetic Testing | No pathogenic mutation | α-thalassemia or β-thalassemia carrier | Recommend PGT-M, especially if both partners are carriers of the same type |
| SMA Carrier Screening | Normal SMN1 gene copy number | SMN1 deletion or mutation | Recommend PGT-M (when both partners are carriers) |
| Expanded Carrier Screening | Negative for hundreds of recessive diseases | Carrier of a pathogenic gene | Assess necessity of PGT-M based on the specific disease |
| AMH + Antral Follicle Count | AMH ≥ 1.2 ng/mL, AFC ≥ 6 | Diminished ovarian reserve | Affects number of eggs retrieved, may reduce number of embryos available for PGT |
Case Scenario Analysis: Thalassemia Carrier Couple Doing PGT in Thailand
Background: A couple from Guangdong. The husband is a carrier of β-thalassemia (mutation site IVS-2-654), and the wife is a carrier of α-thalassemia (--SEA deletion). Both have mild thalassemia, but if a child inherits the pathogenic genes from both parents, they could develop intermediate or severe thalassemia.
Process:
- Completed thalassemia genetic testing in China to confirm the mutation sites.
- Chose a reproductive center in Bangkok, Thailand, with experience in PGT-M. Sent genetic reports in advance for pre-evaluation.
- Custom PGT-M probes were designed (took about 4 weeks).
- The woman underwent ovarian stimulation, yielding 14 eggs, which formed 7 blastocysts. Biopsy was performed and samples sent for testing.
- Test results: 2 embryos were chromosomally normal and did not carry the pathogenic gene, 3 were carriers, and 2 had chromosomal abnormalities.
- Transferred 1 normal embryo, resulting in a successful pregnancy. Prenatal diagnosis confirmed the fetus did not have thalassemia.
This case illustrates: For couples who are carriers of a clear monogenic disease, PGT-M in Thailand can effectively block the transmission of the genetic disease. However, the prerequisites are: ① The pathogenic gene loci are clearly identified; ② The chosen reproductive center has the capability for custom PGT-M probes and testing; ③ There are a sufficient number of embryos available for screening.
Practitioner's Observation: The Real Situation of PGT in Thailand
I have visited and studied at several reproductive centers in Thailand. A real feeling is that the technical hardware for PGT in Thailand is not bad. Most centers use NGS platforms, and their testing throughput and accuracy are among the top in Asia. However, the differences mainly lie in two aspects:
- Embryo Biopsy Step: The experience of the biopsy operator directly affects the embryo survival rate and the reliability of the test results. In skilled laboratories, the survival rate after embryo biopsy can reach over 95%, while in less experienced centers, it might only be around 80%.
- Genetic Counseling Step: The number of local genetic counselors in Thailand is limited. Some centers mainly rely on doctors to double as genetic counselors, and their ability to interpret complex genetic diseases varies. It is recommended that couples with clear genetic disease needs complete their genetic counseling and genetic testing in China before going to Thailand, bringing the reports with them for more efficient communication.
Additionally, the cost of PGT in Thailand is usually included in the "third-generation IVF package," priced around 300,000 to 500,000 Thai Baht (equivalent to RMB 60,000 to 100,000). However, the custom probe cost for PGT-M is extra, about 50,000 to 100,000 Thai Baht. The cost is not significantly lower than in China. The main considerations for choosing Thailand are often greater procedural flexibility and fewer policy restrictions.
How to Determine if You Need to Add PGT for Thai IVF?
The following three questions can help you make a decision:
- Is there a clear history of genetic disease in the family? If yes, it is recommended to do carrier screening first to confirm the pathogenic loci, then assess the necessity of PGT-M.
- Have you experienced recurrent miscarriages or implantation failures? If yes, it is recommended to do chromosomal karyotype analysis and embryo chromosomal analysis to assess the need for PGT-A.
- Is the woman over 37 years old? If yes, even without a clear genetic history, PGT-A can reduce the risk of miscarriage and genetic diseases caused by embryonic chromosomal abnormalities.
What Should You Pay Attention To?
- PGT cannot replace prenatal diagnosis. Even if PGT shows the embryo is normal, amniocentesis or chorionic villus sampling is still recommended during pregnancy for confirmation.
- The technical level and operational standards of PGT vary among different reproductive centers in Thailand. Before choosing, verify the laboratory's qualifications and biopsy success rate.
- Custom probe design for PGT-M takes time, usually 4-6 weeks. The overall treatment cycle will be 1-2 months longer than conventional IVF.
- Not all embryos will pass PGT screening. The number of usable embryos may be lower than expected, so be mentally prepared.
Ending: Risk Reminder
PGT technology in Thai IVF can significantly reduce the risk of genetic diseases, but every technology has its boundaries. De novo mutations, mosaicism, polygenic diseases, and mitochondrial diseases are areas that PGT cannot fully cover currently. Furthermore, the accuracy of PGT results is influenced by the laboratory level, biopsy timing, and testing platform, with the possibility of false negatives and false positives. It is recommended to complete genetic counseling and genetic testing in China first to clarify your own genetic risk type before deciding to go to Thailand, and then choose a reproductive center with the corresponding technical capabilities. PGT is a tool to reduce genetic risk, not a guarantee to eliminate all genetic problems.
