genetic Testing

Choosing an egg donor is one of the most meaningful steps in building your family through donor egg IVF. Among the many important factors to consider (like personal background, physical traits, and education), one of the most medically relevant is your egg donor’s genetic testing summary.

Understanding your donor’s genetic profile helps ensure genetic compatibility between the donor and the sperm source, which reduces the chance of passing on inherited conditions. Whether you’re pursuing a frozen or fresh egg donation, interpreting these results can feel overwhelming at first. But with the right guidance, you can make an informed, confident choice.

In this guide, we’ll help you understand:

• What’s included in an egg donor’s genetic testing summary
• The importance of genetic compatibility in egg donation
• How to interpret terms like “carrier,” “variant of uncertain significance,” and more
• What to do if your donor and sperm source aren’t genetically compatible
• How a genetic counselor can support your journey

At Cofertility, we prioritize transparency and genetic safety. For all fresh and frozen matches, we provide a genetic testing summary. However, during a fresh donation, this happens after the match. All of our donors complete the Fulgent Beacon Expanded Carrier Screening panel which tests for 427 conditions. If you have already completed a different panel, follow-up testing may be recommended for you or your donor. Recommendations for additional testing should be discussed with your reproductive endocrinologist and/or a genetic counselor. 

No matter how you go about it, genetic testing is a big deal, and it’s critical that you fully understand the results for both the egg donor and sperm source. Read on so that you can feel fully informed and confident as you move forward through the donation process. 

Why genetic testing matters in donor egg IVF

Genetic testing plays a vital role in identifying recessive and X-linked conditions that may otherwise go unnoticed. Most people are carriers of at least one genetic condition, even without any symptoms. If both the donor and the sperm source are carriers for the same condition, the risk of having a child affected by that condition increases significantly.

Understanding inheritance patterns

Autosomal recessive inheritance: Both biological contributors must be carriers of the same gene mutation for the child to be at risk. If only one is a carrier, the child is usually unaffected.

X-linked inheritance: This type affects conditions linked to genes on the X chromosome. If a donor carries an X-linked condition and the child is biologically male, he may be at risk.

Think of genes like recipe cards. A mutation is like a typo on the card. If both sets of recipe cards (from egg and sperm) have the same typo, the dish — or baby — might turn out differently than expected. 

In some cases, this could also result in an increased risk of miscarriage or pregnancy loss, especially if the condition is severe and incompatible with life. Some affected embryos may fail to implant or stop developing early on. 

Learn more about carrier screening and inheritance here.

How to interpret genetic testing results

Your egg donor’s genetic profile may include one or more of the following:

1. Chromosome analysis (karyotype)

A karyotype looks at the structure and number of chromosomes. It can detect large-scale abnormalities such as translocations, deletions, or extra chromosomes (e.g., Turner syndrome or balanced translocations). These abnormalities can affect fertility or the health of the resulting embryo.

2. Hemoglobin evaluation

This test screens for conditions like sickle cell disease or thalassemia, which are more common in certain ethnic groups. It assesses the type and quantity of hemoglobin in the blood.

3. Carrier screening

The most extensive and detailed part of the genetic testing summary. It examines hundreds of genes associated with recessive and X-linked conditions.

At Cofertility, whenever possible, we utilize the Fulgent Beacon 427 panel, which tests for over 400 clinically relevant genes, including cystic fibrosis, Tay-Sachs disease, and spinal muscular atrophy (SMA).

Interpreting an egg donor’s carrier screening results

Here are some terms that you may find in your donor’s genetic testing summary:

• “Carrier”: The donor carries one mutated copy of a gene for a recessive or X-linked condition but is not affected. This is common and doesn’t automatically disqualify the donor.
  
• “Variant of Uncertain Significance (VUS)”: A genetic variant was found, but it’s unclear whether it causes disease. These are not typically considered a match-breaking finding.
  
• “Reproductive risk”: This refers to the chance that a child could inherit a condition based on both donor and sperm source being carriers of the same gene.
  

One important note: different labs use different naming conventions and may include different genes in their panels. That’s why it’s crucial to match the donor and sperm source panels, or at least confirm both were tested for the same conditions.

Clinics often have preferred testing labs (like Fulgent, Natera, or Sema4). If you or your donor switch clinics mid-process, your new clinic may accept prior testing as long as results cover the same conditions.

What if the egg donor and sperm source are not a genetic match?

Even with rare mutations, this is possible. When it does, there are several options:

• Genetic counseling: Speak with a licensed counselor to understand your risks and whether additional testing is warranted.
  
• Donor re-selection: If the risk is deemed too high, choosing a new donor is always an option.
  
• PGT-M testing: In some cases, preimplantation genetic testing for monogenic disorders (PGT-M) may be used to select embryos free of the condition.

The role of a genetic counselor

A genetic counselor is a trained healthcare professional who can help interpret complex genetic reports and explain inheritance risks in plain language. They’ll also help you coordinate follow-up testing or next steps and support your emotional well-being throughout the process.

In other words? Genetic counselors are a godsend for average patients who want to clearly understand genetic testing summaries. At Cofertility, we encourage all intended parents to connect with a genetic counselor, especially when navigating genetic compatibility throughout the egg donation process.

FAQs about egg donor genetic testing

What if my donor is a carrier?
That’s common, and not necessarily a concern. What matters is whether the sperm source is a carrier for the same condition.

Can I request additional testing for the donor?
Yes. If your clinic or doctor recommends more targeted screening, it can often be arranged through your Cofertility Member Advocate.

Do I need to be tested too?
If you are using your own sperm or a known sperm source, yes. Your clinic may have already tested you. If not, you can request it as part of the match process.

Why are results from different labs hard to compare?
Each lab uses slightly different panels and reporting methods. That’s why matching the same or equivalent panel is essential to properly assess reproductive risk.

Making informed choices with confidence

Your egg donor’s genetic testing summary is a critical tool in making a safe and informed decision about your path to parenthood. With the right information, plus the support of your clinic and genetic counselor, you can interpret your donor’s results confidently and understand how they align with your family-building goals.

Cofertility is here to support you every step of the way. If you have questions about a donor’s genetic testing summary or want to ensure compatibility, reach out to our team. We’ll help guide you through the process with compassion and clarity.

If you're exploring IVF, you may have heard about karyotype testing. This chromosomal analysis provides valuable information about genetic health, but many people aren't sure what it involves or how it differs from other genetic screening options.

This article explains what karyotype testing is, how it's performed, and its role in fertility treatment. We'll cover how it differs from genetic carrier screening, why some clinics require it for egg donors, and what the results can tell you about your genetic health.

What is karyotype testing?

Karyotype testing is a type of genetic test that examines the number and structure of chromosomes in your cells. These thread-like structures carry your genetic information, with normal human cells containing 46 chromosomes arranged in 23 pairs. Half of each pair comes from the egg, and half from the sperm.

During the test, a medical professional takes a small blood sample. Lab technicians then culture these cells, arrest them during cell division when chromosomes are visible, and arrange photographs of the chromosomes in pairs. This arranged display of chromosomes is called a karyotype.

The process reveals several key pieces of information:

• The total number of chromosomes
• The size and shape of each chromosome
• The arrangement of bands or patterns on the chromosomes
• Any structural changes or abnormalities

Sometimes karyotype testing is called genetic testing, chromosome testing, chromosome studies, or cytogenetic analysis.

What abnormalities can karyotype testing detect?

Karyotype testing can identify several types of chromosomal changes:

• Aneuploidy: Having extra or missing chromosomes. For example, an individual with a third copy of chromosome 21 would have Down syndrome (also known as Trisomy 21). A female with only one X chromosome would have Turner syndrome (also known as Monosomy X).. 
• Structural changes: These include broken, missing, or extra parts, known as deletions or translocations. They can cause a variety of problems depending on which chromosome is affected. These changes can affect fertility, pregnancy outcomes, and child development.

The purpose of the test is to rule out these abnormalities to increase the chances of a successful pregnancy and healthy child. 

How karyotype testing differs from genetic carrier screening 

While both karyotype testing and genetic carrier screening evaluate genetic health, they look at different aspects.

Karyotype testing examines the big picture - the number and structure of entire chromosomes. It can identify major changes like missing or extra chromosomes, or structural rearrangements that affect large segments of genetic material.

Genetic carrier screening, on the other hand, looks for specific mutations within individual genes. These mutations might be very small changes in DNA sequence that could cause inherited conditions, even if the chromosome structure appears normal. A carrier screen will either be targeted (looking for a specific specific gene for a particular disease) or a broader panel of a few dozen to hundreds of genetic conditions.

Think of it this way: karyotype testing is like checking if you have the right number of books (chromosomes) on your shelf and if they're all intact. Genetic carrier screening is like checking specific pages within those books for typos (mutations) that could affect how the genetic information is read.

Why clinics might require karyotype testing

Some fertility clinics require karyotype testing for egg donors, while others consider it optional. Here's why it can be valuable:

• Preventing genetic disorders: Some chromosomal abnormalities can lead to serious developmental conditions. Karyotype testing helps ensure donors don't carry these abnormalities.
• Reducing miscarriage risk: Chromosomal abnormalities are a common cause of early pregnancy loss. By screening donors' chromosomes, clinics can reduce the risk of miscarriage due to chromosomal issues.
• Complementing carrier screening: While karyotype testing identifies large chromosomal abnormalities, genetic carrier screening helps detect recessive genetic disorders. When used together, these two types of screening combine to provide more comprehensive genetic evaluation to increase the odds of achieving a viable pregnancy and healthy child.
• Supporting informed decisions: Results help intended parents and donors make informed choices about fertility treatment.

Obtaining both female and male karyotypes is generally advised. By testing both partners (or donors), intended parents can get the information they need to make informed decisions about their fertility and their future.

Who needs a karyotype test performed?

Several groups of people may benefit from karyotype testing:

• Egg donors: Many clinics require karyotype testing for donors to screen for chromosomal abnormalities that could affect embryo development.
• People experiencing infertility: Doctors may recommend karyotype testing to determine if chromosomal factors are contributing to difficulty conceiving or recurrent pregnancy loss.
• People with family history: Those with a family history of chromosomal conditions or genetic disorders may want testing before starting fertility treatment.
• Children with developmental concerns: Healthcare providers might recommend karyotype testing to identify potential chromosomal causes of developmental delays or other medical conditions.

The testing process

Getting a karyotype test is straightforward:

1. A healthcare provider draws a small blood sample

2. The lab cultures blood cells for about 1-2 weeks

3. Technicians examine cells under a microscope during cell division

4. They photograph and analyze the chromosomes

5. A genetics specialist interprets the results

Results typically take 2-3 weeks. Your healthcare provider will explain what any findings mean for your fertility treatment plans.

Understanding results

Normal results show 46 chromosomes arranged in 23 pairs, written as 46,XX for females or 46,XY for males. Abnormal results indicate variations in chromosome number or structure.

Some variations may not cause health problems, while others might affect fertility or pregnancy outcomes. A genetic counselor can help explain the significance of any abnormal findings.

Limitations of karyotype testing

While valuable, karyotype testing has some limitations. For example, It can't detect small genetic changes that genetic carrier screening might find. Some genetic conditions occur due to tiny DNA changes invisible at the chromosome level.

Plus, results aren't always black and white. Some chromosomal variations have unclear effects on health or fertility.

The test may also miss some mosaic conditions, where some cells have normal chromosomes while others don't.

Making informed decisions

Remember that karyotype testing is just one tool in genetic screening. Used alongside other tests like genetic carrier screening, it helps provide a clearer picture of genetic health and supports informed fertility decisions.

Find out more about donor egg IVF with Cofertility by taking our quick quiz. Our team can help you understand your options and connect you with qualified healthcare providers.