PGT-A, PGT-M, PGT-SR — what is the difference?

Preimplantation Genetic Testing (PGT) is a family of laboratory techniques used to analyze embryos generated by IVF/ICSI before transfer. A small number of trophectoderm cells is biopsied from a blastocyst-stage embryo, amplified, and analyzed using next-generation sequencing or targeted molecular assays.

PGT-A (Aneuploidy) screens embryos for whole-chromosome and segmental aneuploidies. It is most commonly considered in advanced maternal age, recurrent pregnancy loss, repeated implantation failure or after multiple unsuccessful IVF cycles. PGT-A reports an embryo as euploid, aneuploid or mosaic; clinical decisions are based on the report together with morphology, patient history and ethical guidelines.

PGT-M (Monogenic / single-gene disorders) is used by couples who are known carriers of a specific inherited disease — for example beta-thalassemia, cystic fibrosis, spinal muscular atrophy, Huntington disease or hereditary cancer syndromes. PGT-M requires a pre-test workup with linkage analysis and customized probe design.

PGT-SR (Structural Rearrangements) is intended for carriers of balanced reciprocal translocations, Robertsonian translocations or inversions, where the goal is to identify embryos with balanced or normal chromosomal complements.

All three modalities require coordinated work between the reproductive endocrinologist, embryology laboratory and a certified genetics laboratory. Counselling before and after testing is considered standard of care. WFA does not perform PGT; testing is provided by member clinics and partner genetics laboratories under their local regulatory frameworks.