What is the purpose of preimplantation genetic testing for monogenic disorders (PGT-M)?

• A. Screens embryos for the familial pathogenic variant and allows transfer of embryos without the variant.
• B. Screens parents for the familial pathogenic variant.
• C. Screens placental tissue for variants.
• D. Screens tumors for the pathogenic variant.

Answer: (A)

PGT-M is about screening embryos created through IVF for a known family pathogenic variant so that only embryos that do not carry the disease-causing variant are transferred. This allows couples with a monogenic disorder to have children who are not affected by that specific genetic condition, by testing the embryo at the blastocyst stage and selecting those without the variant. It uses a small embryo biopsy and targeted genetic analysis to detect the familial mutation. It’s not about testing the parents, placental tissue during pregnancy, or tumors, which are addressed by other types of testing.