How PGT-M Works for Inherited Disorders in Thailand

What Is PGT-M?

Preimplantation Genetic Testing for Monogenic Disorders (PGT-M) is a technique used during in vitro fertilization (IVF) to identify embryos that carry a specific inherited genetic condition. It is designed for couples who know they are at risk of passing on a single-gene disorder, such as cystic fibrosis, Huntington’s disease, or thalassemia. PGT-M does not guarantee a healthy pregnancy or live birth, and it is not suitable for all patients. The process requires careful planning, specialized laboratory expertise, and a clear understanding of the limitations.

Step 1: Genetic Counseling and Family History Review

Before starting PGT-M, both partners undergo genetic counseling to confirm the diagnosis, identify the specific genetic mutation, and understand the inheritance pattern. The counselor will review family history and may recommend carrier testing for the partner if not already done. This step is essential to determine whether PGT-M is appropriate and to set realistic expectations. In Thailand, genetic counseling is offered at major IVF centers, often in collaboration with geneticists.

Step 2: Probe Development – The Custom Test

PGT-M requires a personalized genetic test, called a probe, that is designed to detect the specific mutation in the family. This is the most time-consuming part of the process. The laboratory needs DNA samples from the couple and, ideally, from an affected family member (such as a child or parent) to build a genetic map around the mutation. The probe uses markers (short tandem repeats or single nucleotide polymorphisms) that are linked to the disease gene. Developing the probe can take several weeks to months, depending on the complexity of the mutation and the laboratory’s workload.

In Thailand, several IVF laboratories have the capability to design custom probes for PGT-M. These labs typically use next-generation sequencing (NGS) or polymerase chain reaction (PCR)-based methods. The probe development is performed in-house or in collaboration with international genetic testing facilities. Patients should confirm with their clinic whether probe development is done locally or sent abroad, as this affects timelines and costs.

Step 3: IVF and Embryo Biopsy

Once the probe is ready, the couple undergoes a standard IVF cycle to produce embryos. After fertilization, embryos are cultured in the laboratory for 5 to 6 days until they reach the blastocyst stage. At this point, a small number of cells (typically 5 to 10) are removed from the trophectoderm (the outer layer that will become the placenta) in a procedure called embryo biopsy. The biopsy is performed by an experienced embryologist using a laser to create a small opening in the embryo’s outer shell (zona pellucida) and gently aspirating the cells. The embryo is then frozen (vitrified) while the genetic analysis is performed.

Thai IVF clinics generally follow international standards for embryo biopsy. The procedure is delicate and requires skilled embryologists to minimize damage to the embryo. The biopsied cells are sent to the genetics laboratory for analysis.

Step 4: Genetic Analysis

The biopsied cells are analyzed using the custom probe to determine whether each embryo carries the mutation. The analysis typically involves amplifying the DNA from the few cells and testing for the specific genetic markers. Results are usually available within 1 to 2 weeks. The laboratory will classify embryos as:

• Unaffected (mutation-free): Embryos that do not carry the disease-causing mutation.
• Affected: Embryos that carry the mutation.
• Inconclusive: Embryos where the result is unclear due to technical issues or insufficient DNA.

It is important to note that PGT-M only tests for the specific mutation requested. It does not screen for other genetic conditions or chromosomal abnormalities unless combined with PGT-A (aneuploidy testing). Some Thai labs offer combined PGT-A and PGT-M, but this should be discussed with the clinic.

Step 5: Embryo Selection and Transfer

Based on the genetic results, the couple and their doctor select one or more unaffected embryos for transfer. The frozen embryo is thawed and transferred into the uterus in a subsequent cycle. Any remaining unaffected embryos can be frozen for future use. Affected or inconclusive embryos are typically not transferred, though some couples may choose to transfer inconclusive embryos after further counseling.

Embryo selection does not guarantee implantation, pregnancy, or a healthy child. Other factors such as maternal age, uterine health, and embryo quality also play a role.

Laboratory Capabilities in Thailand

Thailand has several IVF centers with genetics laboratories capable of performing PGT-M. These labs are often equipped with NGS platforms and PCR machines. However, the availability of custom probe development varies. Some clinics have in-house geneticists who design probes, while others outsource to specialized labs in Thailand or abroad. Patients should ask their clinic:

• Does the lab develop probes in-house or use an external partner?
• What is the estimated timeline for probe development and analysis?
• Is the lab accredited by international bodies (e.g., ISO 15189)?
• Can PGT-M be combined with PGT-A in a single biopsy?

It is also worth noting that Thai regulations may affect the availability of PGT-M for certain conditions. Patients should confirm with their clinic whether the specific disorder is eligible for testing under current guidelines.

Limitations and Considerations

• Not all mutations can be tested: PGT-M works best for well-characterized single-gene disorders. For rare or complex mutations, probe development may not be possible.
• Risk of misdiagnosis: Although rare, errors can occur due to contamination, allele dropout, or recombination. Confirmatory prenatal testing (e.g., amniocentesis) is recommended after pregnancy.
• No guarantee of success: PGT-M does not improve the chance of IVF success. It only reduces the risk of passing on the specific genetic condition.
• Emotional and financial cost: The process is time-consuming and expensive. Probe development alone can cost several thousand dollars, and the overall IVF-PGT cycle adds significant expense.

Alternatives to PGT-M

For some couples, alternatives may include:

• Prenatal diagnosis: Chorionic villus sampling (CVS) or amniocentesis during pregnancy to test for the condition, with the option of termination if affected.
• Donor gametes: Using donor eggs or sperm from a person who does not carry the mutation.
• Preimplantation genetic testing for aneuploidy (PGT-A): If the concern is chromosomal abnormalities rather than a single-gene disorder.

Each option has its own ethical, emotional, and medical considerations. Genetic counseling can help couples weigh the choices.

Questions to Ask Your Clinic

• What is the success rate for PGT-M at your clinic? (Note: success rates vary and should be interpreted cautiously.)
• How many PGT-M cycles have you performed for my specific condition?
• What is the timeline from probe development to embryo transfer?
• What happens if the probe development fails or results are inconclusive?
• Do you offer combined PGT-A and PGT-M?
• What are the costs involved, and are there any guarantees?

For more information, see our PGT in Thailand overview, patient guides, and frequently asked questions.

Frequently asked questions

How long does PGT-M take in Thailand?

The entire process from probe development to embryo transfer can take several months. Probe development alone may take 4 to 8 weeks, followed by an IVF cycle (about 2 weeks), embryo biopsy, and genetic analysis (1 to 2 weeks). Timelines vary by clinic and the complexity of the mutation.

Can PGT-M test for any genetic disorder?

PGT-M is designed for single-gene disorders with a known mutation. It is not suitable for complex conditions caused by multiple genes or environmental factors. The feasibility depends on the specific mutation and the laboratory's ability to design a reliable probe.

Is PGT-M legal in Thailand?

PGT-M is available in Thailand for medical purposes, but regulations may restrict testing for non-medical traits (e.g., gender selection) or certain conditions. Patients should confirm with their clinic regarding legal and ethical guidelines.

What is the success rate of PGT-M?

Success rates depend on many factors, including maternal age, embryo quality, and laboratory accuracy. PGT-M does not increase the chance of pregnancy; it only reduces the risk of passing on the specific genetic condition. Clinics may report their own data, but no universal rate applies.

Continue your research

• PGT in Thailand overview
• PGT and IVF guides
• Frequently asked questions

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.