Can PGT Detect Mitochondrial Disorders in Thailand?

Understanding PGT and Mitochondrial Disorders

Preimplantation genetic testing (PGT) is a technique used during in vitro fertilization (IVF) to screen embryos for genetic abnormalities. However, its ability to detect mitochondrial disorders—caused by mutations in mitochondrial DNA (mtDNA)—is limited. This is due to the unique biology of mitochondria, including heteroplasmy (the presence of both normal and mutated mtDNA within a cell) and the random distribution of mitochondria during cell division.

In Thailand, PGT is available at several fertility centers, but patients with mitochondrial disease concerns should understand what PGT can and cannot do, and what alternative options exist.

At a Glance: Key Points

• PGT-A (aneuploidy screening) does not detect mtDNA mutations.
• PGT-M can be designed for specific nuclear gene mutations but has limited accuracy for mtDNA disorders.
• Mitochondrial replacement therapy (MRT) is not legally available in Thailand.
• Genetic counseling and pre-conception carrier screening are important first steps.

Types of PGT and Their Relevance to Mitochondrial Disorders

PGT-A (Aneuploidy Screening)

PGT-A checks embryos for extra or missing chromosomes. It does not analyze mtDNA and cannot detect mitochondrial mutations.

PGT-M (Monogenic Disorders)

PGT-M is designed for single-gene disorders. For mitochondrial disorders caused by nuclear DNA mutations (e.g., some forms of Leigh syndrome), PGT-M can be effective. However, for mtDNA mutations, PGT-M is less reliable due to heteroplasmy and the difficulty of quantifying mutation load in a single cell biopsy.

PGT-SR (Structural Rearrangements)

PGT-SR detects chromosomal structural changes. It is not relevant for mtDNA disorders.

Limitations of PGT for mtDNA Disorders

• Heteroplasmy variability: The proportion of mutated mtDNA can differ between cells of the same embryo, and a biopsy of a few cells may not represent the whole embryo.
• Threshold effect: Symptoms often appear only when mutation load exceeds a certain threshold, which is difficult to predict from embryo testing.
• Mosaicism: mtDNA mutations can be unevenly distributed, leading to false negatives or positives.
• Technical challenges: Accurate quantification of mtDNA heteroplasmy from a trophectoderm biopsy is not yet standardized.

Alternative Options for Patients with Mitochondrial Disease Concerns

Pre-conception Carrier Screening

Both partners can undergo genetic testing to identify carrier status for nuclear gene mutations that cause mitochondrial disorders. This helps assess recurrence risk.

Prenatal Diagnosis

During pregnancy, chorionic villus sampling (CVS) or amniocentesis can test fetal cells for mtDNA mutations. However, these procedures carry a small risk of miscarriage and may not fully predict postnatal severity.

Donor Egg or Embryo

Using an egg or embryo from a donor with healthy mitochondria can eliminate the risk of passing on mtDNA mutations. This is a widely available option in Thailand.

Mitochondrial Replacement Therapy (MRT)

MRT, also known as “three-parent IVF,” involves replacing faulty mitochondria in the egg with healthy mitochondria from a donor. This technique is not currently permitted in Thailand. Patients interested in MRT would need to explore legal options in other countries.

Questions to Ask Your Clinic

• Does your lab offer PGT-M for mitochondrial disorders? If so, what is the protocol for mtDNA mutation detection?
• How do you handle heteroplasmy assessment in embryo biopsies?
• What are the limitations of PGT for my specific mitochondrial mutation?
• Do you offer genetic counseling for mitochondrial disorders?
• What alternative options (e.g., donor egg) are available?

Next Steps

1. Consult with a genetic counselor to understand your specific mutation and inheritance pattern.
2. Discuss with your fertility clinic whether PGT-M is feasible for your case.
3. Consider pre-conception carrier screening for both partners.
4. Explore donor options if PGT is not suitable.

For more information, see our PGT in Thailand guide, other guides, and FAQ.

Frequently asked questions

Can PGT-A detect mitochondrial disorders?

No, PGT-A screens for chromosomal aneuploidies and does not analyze mitochondrial DNA. It cannot detect mtDNA mutations.

Is PGT-M reliable for mitochondrial DNA mutations?

PGT-M has limited reliability for mtDNA mutations due to heteroplasmy and technical challenges. It may be more effective for nuclear gene mutations causing mitochondrial disorders.

What is the alternative if PGT cannot detect my mitochondrial disorder?

Options include pre-conception carrier screening, prenatal diagnosis, or using a donor egg or embryo. Mitochondrial replacement therapy is not available in Thailand.

Does Thailand allow mitochondrial replacement therapy (MRT)?

No, MRT is not currently permitted in Thailand. Patients interested in this option would need to seek treatment in countries where it is legal.

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.