PGT-M: A guide to testing for inherited genetic conditions in IVF

For many couples going through IVF, balancing hope with caution, understanding medical terminology, and weighing choices that shape your family’s future can feel overwhelming. If you’re facing a known inherited condition, such as cystic fibrosis or Huntington’s disease, the emotional stakes are even higher.

Preimplantation Genetic Testing for Monogenic Disorders (PGT-M) offers a way forward for parents in this position. This screening tool identifies healthy embryos, significantly reducing the likelihood of transmitting serious genetic illnesses. 

This guide explains what PGT-M testing is, when it’s recommended, and how it works. You will learn what conditions it can detect and what the results mean for your next steps. 

What is PGT-M testing, and why is it recommended?

PGT-M testing, previously known as preimplantation genetic diagnosis (PGD), helps identify which embryos carry single gene mutations associated with specific inherited conditions.

PGT-M is especially relevant when there’s a known inherited condition in the family or if both biological parents are carriers of the same genetic disorder. Your doctor may recommend it if:

• You’ve previously ended a pregnancy due to a serious genetic condition

• You already have a child with a genetic disorder and want to reduce the risk of it happening again

• There is a known genetic condition in your family

• There’s a family history of chromosomal abnormalities

• You’ve experienced multiple miscarriages linked to chromosomal issues

Source: Valeriia Svietlova

PGT-M is not a broad screening tool. It is a highly targeted test designed to detect a specific, known mutation. It can only be used when the exact disease-causing genetic variant has been identified in one or both parents.

Here is how one parent described their experience with PGT-M:

[Reddit](https://www.reddit.com/r/IVF/comments/12dvdz0/comment/jf8n2ap/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button)(450)

How does PGT-M in IVF work?

PGT-M always takes place in the context of IVF, even if you have no fertility issues, because testing must be done on embryos fertilized and developed in the lab before they’re transferred to the uterus. 

Here’s how it works:

1. Embryo creation through IVF: Eggs are retrieved and fertilized with sperm in a lab, creating embryos.

2. Embryo biopsy: A few cells are carefully removed from each embryo, typically at the blastocyst stage (5–6 days after fertilization).

3. PGT test development (making a probe): Each PGT-M test must be customized to the family’s unique genetic background, taking into account carrier status, ethnic background, and family medical history.

4. DNA analysis: The extracted cells are tested for a specific mutation linked to the inherited disorder of concern.

5. Embryo selection: Only embryos that do not have the targeted genetic condition and are not carriers are considered for transfer.

Source: Nappy

Embryos are often frozen after biopsy and transferred in a later IVF cycle once results are available. This approach is called frozen embryo transfer and is now more common than fresh transfer because it allows more time for careful genetic analysis.

What is PGT-M probe development?

For the PGT-M test to be accurate and effective for your specific situation, customized PGT test development is necessary. This is a careful, personalized preparation phase that lays the groundwork for testing your embryos.

In the past, this process involved creating a physical “probe” to detect a specific gene mutation, which is why you might still hear the term “PGT-M probe development.” Today, labs use advanced techniques to analyze DNA samples from parents and possibly other family members and build a detailed genetic map linked to the condition being tested for.

Several factors influence how PGT test development unfolds, including:

• The specific genetic mutation involved

• Your family’s unique DNA patterns

• The testing technology available

In most cases, a reliable and customized PGT-M test can be successfully developed. Once this step is complete, your IVF cycle can move forward more clearly.

Is PGT-M safe for the embryo?

PGT-M is considered to be safe for the embryo. There is no evidence to suggest that babies born following PGT-M treatment experience more health or developmental issues than babies conceived via IVF without PGT-M. 

The process involves removing a few cells from the trophectoderm — the cells that will develop into the placenta. This allows the inner cell mass, which will form the baby, to remain undisturbed.

It’s natural to worry about risks, but the embryo biopsy survival rate is higher than 95%. While there is a slight chance of embryo damage during the biopsy, most embryos go through it safely. 

Source: Daniel Reche

How long does PGT-M take, and how accurate is it?

Developing a personalized PGT-M test typically takes around three weeks. However, this process can extend up to six weeks for more complex or rare genetic conditions. You can typically expect test results about 15 days after the lab has received the embryo samples.

Many families find the waiting period for PGT-M challenging but worthwhile. One parent shared their experience on Reddit:

[Reddit](https://www.reddit.com/r/IVF/comments/12dvdz0/comment/jfeyf2k/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button)(450)

PGT-M is generally highly reliable, with over 97% accuracy. Still, no test is perfect, so there’s a small chance the results could be inaccurate, or the test might fail. Plus, PGT-M only looks at one aspect of embryo health — conditions caused by mutations in only one gene.

💡 Tip:

PGT-M is invaluable for detecting specific genetic conditions, but it doesn’t provide insights into chronic or late-onset conditions, like Alzheimer’s disease, breast cancer, prostate cancer, type 2 diabetes, and more. Parents with a family history of these diseases can opt for a new analysis known as PGT-P.

Already did PGT-P? Nucleus Embryo helps you understand and select your embryo based on what matters most to you. Uncover your future child’s risks for common chronic diseases, psychiatric conditions like depression and anxiety, and traits that run in your family, like hair and eye color.

With its detailed, easy-to-understand reports, Nucleus helps you understand the overall potential health of your embryos to add clarity to the complex decision-making process.

Try Nucleus Embryo to gain deeper insights and make more confident decisions for your family’s future.

What conditions can PGT-M detect?

PGT-M can test for almost any genetic condition where the underlying specific gene mutation is known. 

See some of the most common conditions for which PGT-M is used below:

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How PGT-M works with other genetic testing methods

PGT-M is one of three types of preimplantation genetic testing offered today, alongside PGT-A, PGT-P, and PGT-SR. All four tests can be done simultaneously, which is highly beneficial as it provides a more comprehensive picture of each embryo’s genetic health. 

Let’s explore how these tests compare and how they can help you make the most informed decisions possible.

PGT-A vs. PGT-M

PGT-A helps identify embryos with the correct number of chromosomes, typically 46 (23 pairs). This is important because having too few or too many chromosomes (a condition known as aneuploidy) can lead to failed implantation, miscarriage, or serious genetic conditions.

PGT-A does not identify specific inherited diseases, but it can reveal:

• Trisomy: Embryos with too many chromosomes (e.g., Trisomy 21 or Down syndrome)

• Monosomy: Embryos with too few chromosomes (e.g., Turner syndrome)

• Mosaicism: Embryos where some cells are normal and others have chromosomal abnormalities

Even if an embryo is free of a known single-gene disorder, it still needs to be chromosomally normal (euploid) to have the best chance of resulting in a healthy pregnancy. That’s why PGT-A and PGT-M are often done together.

Source: Pavel Danilyuk

PGT-SR vs. PGT-M

While PGT-M screens embryos for a specific single-gene mutation known to run in the family, PGT-SR detects chromosomal rearrangements (translocations, inversions, and duplications) in embryos. These structural changes can affect fertility, pregnancy outcomes, or the baby's health.

There are two possible chromosomal rearrangements:

1. Balanced: Parts of chromosomes have swapped places, but all the genetic material is still present, just rearranged 

2. Unbalanced: Genetic material is lost or increased

The carrier of the balanced chromosomal rearrangements is usually healthy and unaware of the condition because no genetic material is missing. However, when this rearrangement is passed on to a child, it doesn’t always remain balanced. 

The embryo may inherit an unbalanced rearrangement, meaning there's missing or duplicated genetic material. This can lead to serious consequences, such as early miscarriage (the most common outcome), stillbirth, birth defects, or developmental disabilities.

This type of testing is often recommended if:

• A parent is known to carry a balanced chromosomal translocation

• There's a history of recurrent miscarriage or unsuccessful IVF cycles

• A previous child was born with a chromosomal condition

Bonus read: Learn about PGT-P, a newer addition to preimplantation genetic testing that detects polygenic risk. 

PGT-M testing limitations

While PGT-M can help reduce the risk of passing on a known genetic disorder, it’s important to understand what it can and cannot do:

PGT-M can’t detect common conditions, such as diabetes, heart disease, or psychiatric conditions like depression, anxiety, and ADHD — to get those insights, you need to go for the more advanced PGT-P testing.

In fact, PGT-M can help identify the most viable embryos only when paired with other options like PGT-A, PGT-SR, and PGT-P.

Genetic optimization software such as Nucleus Embryo makes transparent embryo selection a reality: you can upload the genetic data from your PGT-P or whole-genome analysis on your embryos, and Nucleus will screen your embryos for chronic and late-onset conditions such as cancers and Alzheimer’s disease, as well as provide insights into your future child’s eye color, hair color, height, and more s, offering a broader, comparable view of your embryos’ health potential.

That way, you gain clarity and make more informed decisions about your future family.

Nucleus Embryo: Confidence beyond standard genetic testing

After PGT-M, you may find yourself facing a new kind of uncertainty: choosing between multiple embryos that are all considered “healthy” by clinical standards. Nucleus Embryo can help you evaluate your options.

Nucleus Embryo is not a replacement for clinical testing but a supplemental tool designed to add clarity and confidence to one of the most important decisions you’ll ever make. It uses embryo DNA data you obtained from PGT-P or whole-genome testing on your embryos, analyzes it, and screens for a much higher number of diseases and even potential traits. 

Nucleus builds on the information you’ve received from your fertility clinic and gives you the option to take a deeper look at what makes each embryo genetically unique.

If multiple embryos are eligible for transfer, Nucleus helps you compare them side by side — not just for disease risk, but for a range of additional insights. Here’s what it can show you:

• Chronic and late-onset conditions like Alzheimer’s disease, cancers, heart disease, and more.

• Rare variant screening for hereditary conditions

• Predictions for traits, such as height or hair color

Results are shared through an interactive embryo comparison dashboard, giving you a clear, visual way to explore each embryo’s profile. Instead of a static report, you can compare traits and risks in one place, making it easier to weigh your options. 

Every detail is explained in simple terms — only straightforward insights you can actually use.

If you want even more context, Nucleus also offers carrier screening, helping pinpoint inherited diseases that you and your partner could pass on to your future children. Thanks to cutting-edge genomics and data analysis, you can get multigenerational insight.

How Nucleus Embryo works

Nucleus Embryo fits seamlessly into the IVF process you’ve already started. Here’s how it works:

1. Ask your clinic for PGT-P testing with LifeView by Genomic Prediction

2. Sign up for Nucleus Embryo during or after you complete your IVF cycle

3. Request your embryos’ PGT-P DNA data from your clinic

4. Upload the data to Nucleus Embryo and analyze the embryo analysis report

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Featured image source: Anastasiya Gepp