Beyond the Test Panel: What Patients and Providers Still Miss About Genetic Testing

About the expert

Andria Besser, MS

The Director of Reproductive Genetics at the NYU Langone Fertility Center and as Clinical Instructor in the Department of OBGYN at NYU Grossman School of Medicine.

Andria Besser, MS, currently serves as the Director of Reproductive Genetics at the NYU Langone Fertility Center and as Clinical Instructor in the Department of OBGYN at NYU Grossman School of Medicine. She is a board-certified Genetic Counselor and has been specializing in assisted reproductive technologies for over 15 years. Her main focus is on preimplantation genetic testing, donor gametes, and preconception counseling.

Silvia:

When speaking with providers and patients, I get the sense that there are different interpretations of what it actually means to have manifesting carrier status. What are we missing?

Andria:

Even though we’ve known for some time that certain conditions can present with manifesting carrier status—meaning a person who’s just a carrier of a recessive condition might still show symptoms—this hasn’t been widely acknowledged in practice. Historically, we believed carriers were unaffected. Now, we know that carriers can sometimes show symptoms, either related to the condition or even entirely different.

That said, this topic is only just beginning to be discussed more openly, as we better understand some of the genes on these recessive carrier screening panels. I don’t think it’s consistently being talked about with patients. There was a study a couple of years ago that found about 25% of patients reported they weren’t informed about their manifesting carrier status—even though it was part of their results. It's unclear whether that was due to a lack of documentation or just patient recall, but either way, there’s a disconnect.

Even among providers, there's a big misconception: if a couple doesn’t both carry the same condition, the assumption is that no further discussion is needed. Providers may refer high-risk couples for genetic counseling, but if one partner is positive and the other is negative, that conversation often just doesn’t happen.

Silvia:

At LEVY Health, we work with different clinics and egg donation agencies, and everyone seems to have different requirements for genetic testing and counseling. Many go for the most comprehensive option, and when I ask why, the answer is often: liability. From a pragmatic, medically relevant point of view—what would you recommend?

Andria:

The American College of Medical Genetics and Genomics provides guidance with lists of recommended conditions. However, it’s tricky to align that with the panels available. There are so many products on the market, and the differences go far beyond just which genes are included.

A major factor is how results are reported. Labs vary widely in how they classify variants: one might flag a variant as pathogenic, while another calls it a variant of uncertain significance. So, testing the same gene at two different labs could yield two different results. That’s not necessarily because one is right and one is wrong—they may simply interpret and report the same data differently.

Some labs provide clear, detailed reports, including whether a variant is on the mild or severe end of a spectrum, or whether it’s only pathogenic in combination with certain other variants. Other labs just list what they found and leave the interpretation to you. Some report manifesting carrier status; others don’t.

So, the issue isn’t just the panel contents but also how the information is delivered. We need more standardization—not just of what’s tested, but how it’s reported.

Silvia:

We see that a lot when it comes to gamete donors. Often, the donor and the recipient were tested with completely different panels.

Andria:

Exactly. At our center, we have an entire team dedicated to donor matching reviews. Ideally, this wouldn’t be necessary if there were standardized panels across the board.

Silvia:

Let’s take a look at PGT-A. From your perspective, what are the biggest misconceptions about what PGT-A can do?

Andria:

The number one misconception is that PGT-A is a health screen. Many patients think it screens for all health concerns, and they’re shocked when, for example, a baby is born with a heart defect or something else shows up during pregnancy.

There’s this belief that because the embryo was genetically tested, everything was “checked.” But really, PGT-A is not a health screen—it’s a viability test. That word—viability—needs to become more common in how we talk about this. It’s about identifying embryos that are less likely to implant or result in a successful pregnancy, not about choosing the “healthiest” embryo.

Silvia:

PGT-A results sometimes come back as neither clearly normal nor abnormal. How should those gray-area results be explained to patients?

Andria:

That explanation needs to start before testing. Patients should know upfront that results are not always black-and-white—an embryo may be labeled as “mosaic” or have a “segmental aneuploidy,” and we may not know what that means for viability.

It’s essential that whoever is doing the counseling understands the latest data—particularly that embryo mosaicism is not the same as mosaicism in a prenatal test like CVS or amniocentesis. The risks and implications are very different, and patients need to be counseled accordingly.

We rely on outcome data from embryos—not hypothetical risks or extrapolations from other testing types. So if we have data from the lab, or from studies using the same PGT-A technology, we use that to provide numbers about implantation or viability probabilities. We also talk about the chances of persisting mosaicism in a resulting pregnancy, which we now know is very, very low—but not zero.

It's also important to compare what we don’t know about mosaic embryos with what we don’t know about euploid embryos. Neither is guaranteed to result in a healthy baby.

Silvia:

How do you assess whether a couple really understands all of this well enough to make informed decisions?

Andria:

It's always tricky. We try techniques like asking them to explain things back in their own words, asking what their biggest takeaway or concern is, and checking for consistency with what we’ve explained.

Where we see understanding break down most often is actually with euploid embryos. When something unexpected happens in those pregnancies, it becomes clear that some patients believed PGT-A meant their baby would be “healthy.” And while that misunderstanding is understandable—it’s still a sign that we need to do better at explaining what’s actually being tested.

Silvia:

What’s the best terminology to describe mosaic embryos?

Andria:

The term mosaic came from those original mixing experiments where researchers combined euploid and aneuploid cells to see how they’d show up on a PGT-A plot. But now we know that those same “intermediate copy number” patterns on the plot can be caused by other things, not just mosaicism.

Intermediate copy number is actually the more accurate term. You can’t really see mosaicism in a single biopsy—because it’s a pooled sample. You’d need two separate biopsies—one normal, one abnormal—to actually confirm mosaicism.

Silvia:

What are your personal takeaways from the recent PGT-A lawsuits? What should physicians and patients be paying attention to when it comes to thresholds and discarding embryos?

Andria:

From what I understand, the lawsuits are more about the marketing of PGT-A—using words like “accurate” or “clear”—rather than about actual clinical practice or lab accuracy. It’s similar to what happened with NIPT lawsuits a few years ago.

Clinically, what’s important is that physicians really understand the platform their lab uses for PGT-A. Not all platforms are the same. They should be asking labs about their validation studies, margins of error, and the data behind embryo viability predictions. Sometimes labs say, “We don’t make transfer decisions,” and clinicians say, “We’re relying on the lab,” and patients end up caught in the middle. It’s crucial that the communication is clear, evidence-based, and consistent—so patients aren’t left making impossible decisions without proper guidance.

When we do get those results, the key is to make sure the person doing the counseling understands the latest data. There’s a difference between embryo mosaicism and prenatal mosaicism from a CVS or amnio test. We need to use data from embryos—not assumptions or extrapolations from prenatal testing.

We need more transparency and evidence-based communication—so that patients aren’t left to navigate all of this alone. Everyone involved needs to be clear about what the results actually mean.

Silvia:

So the takeaway is: ask more questions, be more transparent—on both sides?

Andria:

Absolutely.

Silvia:

Thank you so much for the interview!