What is PGT-M, when is it considered, and how does the process work? Misdiagnosis, limits and questions for your doctor according to ESHRE recommendations.
PGT-M is the search, in a few cells taken from an embryo obtained through IVF, for the variant that causes a known single-gene (monogenic) disease in the family of a couple. It is not a screening but a diagnostic approach aimed at a particular family variant. Even so, the possibility of misdiagnosis does not disappear completely, and the test gives no assurance about the baby's health. The process starts with genetic counselling; whether the test can be applied in your family is assessed together by the doctor and the genetic counselling process.
How is the purpose of PGT-M separated from that of PGT-A?
PGT-A screens the chromosome number in the embryo and does not target a known disease in the family. PGT-M, on the other hand, looks for a single, previously identified variant. For this reason the two tests differ in purpose, evidence framework and manner of assessment; the "not recommended routinely" assessment that applies to PGT-A cannot be carried over to PGT-M.
Do PGD and PGT-M describe the same approach?
The old name of PGT-M is preimplantation genetic diagnosis (PGD). Today the term PGT-M is used for the same approach.
Which features of the variant in your family are assessed for PGT-M?
According to the current organisational recommendations prepared for Europe, the variant to be looked for in PGT-M must be disease-causing and found to be linked to serious health effects.
Is PGT-M offered to you as the only option?
The current recommendations on this subject ask that counselling not be directive and that it cover all reproductive options. That is, PGT-M is not presented as the only route for a couple who carry a variant.
How are genetic counselling and family-specific preliminary work done?
The current assessment on this subject gives method and strategy recommendations for PGT-M. In practice the process starts with your couple's variant being examined in the laboratory and the test being adapted to your family. This preparation is mostly a separate stage carried out before the IVF cycle.
How does the process move from IVF to the decision on testing and transfer?
Your embryos are created in an IVF or ICSI cycle. According to the current assessment on this subject, ICSI may be necessary in special situations such as PGT cycles. A few cells are sampled from the outer layer of the embryo; in this sample it is investigated whether the known variant of your family is present. The sampling technique is a separate subject. When the report is out, the transfer plan is determined with your doctor and in the genetic counselling process.
Can there be a misdiagnosis, or an embryo that cannot be diagnosed?
The current assessment on this subject states that the risk of residual misdiagnosis that may arise from recombination, allele dropout and contamination should be assessed and reported. A clear diagnosis may not be reached in some embryos. Laboratories are asked to validate their workflows before clinical use. In addition, a mosaic result in the cell sample can also affect the accuracy of the diagnosis; the details are a separate subject.
Are the risks of the IVF process assessed separately?
Because the test is done on the embryo, it brings no direct procedure risk to you. However, IVF stages such as ovarian stimulation, egg collection and embryo transfer have their own risks. Their scope should be discussed with your doctor.
Can PGT-M and PGT-A be done together?
Yes. According to the current assessment on this subject, when PGT-M and PGT-A are carried out together, this practice is called "comprehensive PGT". If such a plan is being considered, you need to receive comprehensive counselling on the possible findings and their effect on the choice of transfer.
When are counselling and emotional support offered?
According to the current recommendations on this subject, counselling should be offered before and after the cycle and, if possible, should include both partners. The likelihood of pregnancy and live birth, multiple pregnancy, the limits of the test, the possibility of error and the fate of embryos that cannot be diagnosed are addressed in this consultation. Psychological support should also, if possible, be offered before, during and after the cycle. The process can be demanding; you can share these feelings with your doctor. The same recommendations suggest that cost, duration and social or psychological effects be discussed from the start.
What questions can you ask your doctor and genetic counsellor?
- Is it technically possible to apply this test for the variant in our family?
- What does the preliminary work cover, and how much time may be needed before the IVF cycle?
- What is in the result report, and how are embryos that cannot be diagnosed approached?
- What are the pros and cons of this route compared with other reproductive options?
- Is there an additional cost for the test?
Frequently Asked Questions
If a pregnancy occurs with PGT-M, is prenatal diagnosis still needed?
Yes, the current recommendations on this subject advise that prenatal diagnosis be offered for all pregnancies that occur after PGT; the possibility of misdiagnosis has not disappeared. The doctor who follows your pregnancy determines the suitable method and timing.
What happens if no suitable embryo is found?
The organisational recommendations on this subject ask that having no embryo that can be transferred at all be addressed from the start in counselling. The mosaicism recommendations, on the other hand, state that one more IVF cycle can be done in order to reach an embryo correctly diagnosed for PGT-M. Your situation and preferences determine the decision.
Can PGT-M be done for every genetic disease?
No. The current recommendations on this subject advise that PGT be done only where the genetic diagnosis is technically feasible and reliable. Variants of uncertain significance, which do not predict a phenotype, should be excluded from PGT.
Is the long-term health of children born with IVF and PGT known?
The current assessment on this subject states that there is uncertainty about the long-term effect of IVF and PGT methods and recommends a minimum data set for following the children. In other words, the data in this area are still limited.
Does PGT-M look for a particular variant in the family?
Yes. PGT-M is a diagnostic approach that targets the single-gene variant previously identified in your family; it is not a general chromosome-number screening.
Does the statement that PGT-A is not recommended routinely also apply to PGT-M?
No. The purpose, evidence framework and manner of assessment of these tests are different. The assessment of PGT-A cannot be carried over to PGT-M.
Can the preliminary work be done before IVF?
Yes. Examining your family variant and adapting the test to your family is mostly a separate stage before the IVF cycle.
If PGT-M is done, does the possibility of misdiagnosis disappear completely?
No. Residual misdiagnosis risk may exist for reasons such as recombination, allele dropout and contamination. A clear diagnosis may not be reached in some embryos.
Can PGT-M and PGT-A be carried out together?
Yes. This practice is called comprehensive PGT. The possible findings and their effects on the choice of transfer need to be discussed in counselling.
Does PGT-M show that the baby will be healthy in all respects?
No. The test targets a particular family variant; it gives no assurance about the baby's health, and the possibility of misdiagnosis does not disappear completely.
Is it recommended that both partners attend counselling?
Yes. It is recommended that counselling, if possible, cover both partners and be offered before and after the cycle. Psychological support may also be considered throughout the process.
Get Your Free Consultation
Fill out the form below and our team will contact you
