At a glance
Understand the difference between PGT-A and PGT-M when considering HLA-matched embryos in Thailand, and why PGT-A alone cannot select for tissue compatibility.
Understanding PGT-A and PGT-M
Preimplantation genetic testing (PGT) is a set of techniques used to screen embryos created through IVF before transfer. Two common types are PGT-A and PGT-M. PGT-A (aneuploidy testing) checks embryos for an abnormal number of chromosomes, which can affect implantation or lead to miscarriage. PGT-M (monogenic testing) looks for specific single-gene disorders, such as thalassemia, and can also be used to identify embryos with a particular tissue type, known as HLA matching.
For patients who already have a child with a condition like thalassemia or a blood disorder, PGT-M can help select an embryo that is both free of the genetic condition and a tissue match for the existing child. This allows the birth of a healthy sibling whose umbilical cord blood or bone marrow could potentially be used for treatment.
Why PGT-A Alone Is Not Enough for HLA Matching
HLA (human leukocyte antigen) typing is a genetic test that determines tissue compatibility. PGT-A does not examine HLA genes; it only counts chromosomes. Therefore, PGT-A cannot tell you whether an embryo is a match for a sibling. To achieve HLA matching, PGT-M must be performed using a specific test designed to identify the HLA type of each embryo.
In some cases, clinics may combine PGT-A and PGT-M in the same IVF cycle. This means embryos are screened for both chromosomal abnormalities and the specific genetic condition, as well as HLA type. However, PGT-A alone will not provide the information needed for HLA matching.
How PGT-M for HLA Matching Works in Thailand
In Thailand, PGT-M for HLA matching is offered at specialized fertility centers. The process typically involves several steps:
- Consultation and genetic counseling: You will meet with a fertility specialist and a genetic counselor to discuss your family history, the genetic condition involved, and the feasibility of HLA matching.
- IVF cycle: You undergo ovarian stimulation and egg retrieval, and the eggs are fertilized with sperm in the laboratory to create embryos.
- Embryo biopsy: A few cells are removed from each embryo, usually on day 5 or 6 of development.
- Genetic testing: The biopsied cells are sent to a genetics laboratory for PGT-M, which includes testing for the specific genetic disorder and HLA typing.
- Embryo selection: Only embryos that are both unaffected by the genetic condition and HLA-matched to the existing child are considered for transfer.
- Frozen embryo transfer: A suitable embryo is thawed and transferred to your uterus.
It is important to note that the entire process requires careful planning and coordination between the fertility clinic and the genetics laboratory. Not all clinics in Thailand may offer PGT-M for HLA matching, so you will need to confirm availability and specific protocols with the clinic you choose.
Key Differences Between PGT-A and PGT-M
| Aspect | PGT-A | PGT-M |
|---|---|---|
| Purpose | Screen for chromosomal abnormalities (aneuploidy) | Detect specific single-gene disorders and HLA type |
| What it tests | Number of chromosomes | Specific gene mutations and HLA markers |
| Can it select for HLA match? | No | Yes, when designed for that purpose |
| Typical use | To improve implantation chances and reduce miscarriage risk | To avoid passing on a genetic disease and to find a tissue match for a sibling |
| Combination | Often used alone or with PGT-M | May be combined with PGT-A for additional screening |
Considerations for Patients Seeking HLA-Matched Embryos
If you are considering PGT-M for HLA matching in Thailand, there are several factors to keep in mind:
- Genetic counseling: You will need to understand the inheritance pattern of the condition and the probability of having an HLA-matched, unaffected embryo. This is not guaranteed, and the number of suitable embryos may be limited.
- Legal and ethical aspects: HLA matching for the purpose of creating a “savior sibling” may be regulated in some countries. In Thailand, you should discuss the legal framework with your clinic and possibly seek independent legal advice.
- Cost: PGT-M for HLA matching is more complex and expensive than standard PGT-A. Costs can vary significantly between clinics, so you should request a detailed breakdown.
- Time: The entire process, from initial consultation to embryo transfer, may take several months. Be prepared for potential delays.
- Success rates: The chance of achieving a pregnancy and a live birth depends on many factors, including your age, the number of embryos available, and the quality of the laboratory. No clinic can guarantee a successful outcome.
Questions to Ask Your Clinic
Before proceeding, consider asking the following questions:
- Does your clinic offer PGT-M for HLA matching?
- What is the experience of your genetics laboratory with HLA typing?
- How many embryos are typically needed to have a reasonable chance of finding an HLA match?
- What is the cost of PGT-M for HLA matching, and what does it include?
- Are there any legal restrictions in Thailand regarding HLA matching?
- What is the timeline from start to embryo transfer?
Next Steps
If you are ready to explore PGT-M for HLA matching in Thailand, here is a simple checklist:
- Research fertility clinics that offer PGT-M and have experience with HLA matching.
- Schedule a consultation to discuss your specific situation.
- Ask for a referral to a genetic counselor who can explain the testing process and implications.
- Request a detailed cost estimate and timeline.
- Clarify any legal or ethical questions with the clinic or a legal professional.
For more general information about PGT in Thailand, you can visit our PGT in Thailand page. You may also find our guides helpful, and check our FAQ for common questions.
Frequently asked questions
Can PGT-A be used for HLA matching?
No, PGT-A only screens for chromosomal abnormalities and does not test HLA type. HLA matching requires PGT-M, which is specifically designed to identify tissue compatibility.
Is PGT-M for HLA matching available in Thailand?
Yes, some fertility clinics in Thailand offer PGT-M for HLA matching, but availability may vary. You should confirm with the clinic directly and ask about their experience with this specific testing.
What is the success rate of PGT-M for HLA matching?
Success rates depend on many factors, including the number of embryos produced, the genetic condition involved, and the laboratory's expertise. There is no guarantee of finding an HLA-matched embryo or achieving a pregnancy. Discuss your individual chances with your clinic.
Is PGT-M for HLA matching legal in Thailand?
Legal regulations may apply to HLA matching for medical purposes. It is essential to consult with your clinic and possibly seek legal advice to understand the current legal framework in Thailand.
Continue your research
Medical information notice: This article is educational and does not replace individual assessment, diagnosis, genetic counselling or treatment advice from a licensed clinician. Provider services, availability, fees and policies should be verified directly before booking.
Need help turning research into a shortlist?
