PGT-A, PGT-M, PGT-SR, and PGT-P, Explained

Most people do not start IVF hoping to learn a new genetics vocabulary. Then suddenly there are reports, acronyms, lab calls, and phrases like "euploid" or "polygenic risk."

Here is the simplest way to think about it: PGT is not one test. It is a family name for different embryo genetic tests done before transfer. PGT-A, PGT-M, PGT-SR, and PGT-P each ask a different question.

The fastest way through the alphabet soup is to turn each letter back into the question it actually asks. There are four.

The four questions, at a glance

Which embryos have the expected number of chromosomes?

That is PGT-A — preimplantation genetic testing for aneuploidy. It checks a small sample of cells for missing or extra whole chromosomes, and it is the most common type. What it does not do is screen for single-gene conditions, family-specific variants, or common-disease risk. ACOG's PGT guidance keeps PGT-A, PGT-M, and PGT-SR separate precisely because they answer different questions.

Did an embryo inherit a specific condition that runs in our family?

That is PGT-M — for a monogenic, single-gene condition. It is used when a family already has a known variant, such as a cystic fibrosis or BRCA variant, and checks whether a given embryo inherited that one specific change. It is targeted by design; it is not a search for every possible condition.

Could an embryo inherit an unbalanced chromosome rearrangement?

That is PGT-SR — for a structural rearrangement. It comes up when one partner carries a balanced translocation or inversion. That parent is healthy, but the rearrangement can pass to an embryo in an unbalanced form, which is what PGT-SR is built to catch.

Among these embryos, how do risk estimates for common conditions compare?

That is PGT-P — polygenic. It estimates inherited risk for conditions shaped by many genes at once and compares sibling embryos. It does not diagnose a future child, remove risk, or guarantee health — and ASRM's 2026 ethics opinion describes it as nascent and unproven, not recommended for clinical use at this time.

The catch: a reassuring answer to one of these questions tells you nothing about the other three. "The embryo was tested" only means something once you know which question was asked — a normal PGT-A result, for instance, says nothing about a family BRCA variant unless PGT-M was ordered.

Where Reticular fits

Reticular works in the polygenic layer — risk estimates for selected conditions influenced by many genetic differences. That is separate from embryo grading, PGT-A, PGT-M, PGT-SR, and prenatal testing, and it is context for a decision, not a promise, a diagnosis, or a replacement for your clinic's judgment.