PGT-M and Monogenic Disease Testing: Which Families Need Genetic Counseling?

PGT-M is a type of preimplantation genetic testing used for families with a known risk of a monogenic disease. Unlike PGT-A, which focuses on chromosome number, PGT-M focuses on a specific pathogenic variant or genetic condition.

PGT-M is highly individualized. Each family may have a different gene, inheritance pattern, family structure and testing challenge. It should not be understood as a general embryo screen, but as a targeted testing strategy developed through genetic counseling and laboratory planning.

PGT-M may be considered when both partners carry a recessive condition, when one partner carries a dominant pathogenic variant, or when there is X-linked disease risk. Some mitochondrial DNA conditions or HLA-related situations may require special planning.

Genetic counseling is essential before PGT-M. Counselors help families understand inheritance, reproductive risk, testing feasibility, possible results and ethical issues. PGT-M targets known risk and cannot rule out all diseases. Prenatal screening or diagnosis may still be relevant.

Before PGT-M, the familial pathogenic variant usually must be confirmed. Samples from the couple and sometimes relatives may be needed. A customized testing strategy may need to be developed and validated before the IVF cycle.

During IVF, embryos are cultured and biopsied at an appropriate stage. The biopsy sample is tested according to the established strategy. Results are reviewed with the medical and genetics team. The number of transferable embryos may depend on ovarian response, fertilization, embryo development and test results.

PGT-M cannot guarantee pregnancy or a healthy child. It reduces risk for a known condition but does not predict all future health outcomes. Ethical considerations may arise for adult-onset conditions or conditions with variable severity.

PGT-M can be valuable for selected families, but it requires careful counseling, testing design and informed consent. This article is for educational purposes only and does not constitute medical advice.