You’ve probably heard of DNA tests that tell you about your ancestry — but what about those that look ahead, not back? This is called carrier screening — a test that, in the context of family planning, can reveal if you carry genetic variants that could be passed down to your children.
Since most carriers don’t show symptoms, you might not know you’re at risk until you get tested. Even then, many people aren’t sure what to do with the results.
In this article, we’ll answer the question “What is carrier screening?” and walk you through why it’s important, how it works, and what to do if you’re a confirmed carrier.
What is a carrier screening test?
Carrier screening is a genetic test that checks if you carry any genes that could potentially cause inherited health conditions for your children. The test looks for changes (variants) in your DNA linked to specific genetic disorders.
Carriers usually don’t have any symptoms, so genetic conditions can quietly run in families for generations without anyone realizing it. Carrier screening is therefore valuable because it brings what’s hidden into view before it affects your family.
To understand how this works, it’s helpful to know how genes are inherited and how genetic conditions are classified.
Everyone gets two copies of each gene — one from each biological parent, but not always. Genetic conditions tied to these genes are either classified as dominant or recessive:
Dominant disorders require just one gene variant to cause the condition.
Recessive disorders only occur when both copies of a gene have variants.
This means that if you inherit just one gene variant while the other copy is normal, you’re a carrier — but if both copies have variants, you’re more likely to develop the condition.
Why are carrier screening tests done?
Carrier tests are often recommended or chosen voluntarily for the following reasons:
Pregnancy and family planning
Family history of inherited conditions
Having a high-risk ethnic background
Health reasons
In the sections that follow, we’ll explore each of these reasons in detail.
1. Pregnancy and family planning
If you’re thinking about starting a family or are already expecting, carrier screening can help you and your partner understand your combined genetic risks. If both of you carry the same condition, there’s a higher chance of passing it to your child.
Knowing this early, whether before or during pregnancy, gives you more time to explore your options, like prenatal genetic testing or IVF with genetic screening. That way, you can make decisions that feel right for you with the information in hand.
2. Family history of inherited conditions
Maybe you have a sibling or cousin with a genetic condition like cystic fibrosis or Tay-Sachs. Even if you’ve never shown symptoms yourself, you may still carry the gene. Carrier screening helps you understand your own risk — not just for your health, but also for your future children.
For many people with a family history or genetic conditions, carrier screening offers clarity on lingering questions and peace of mind for planning ahead.
3. Having a high-risk ethnic background
Your ethnic background can make it more likely that you carry certain genetic conditions. For example, about 1 in 25 people of Ashkenazi Jewish descent are carriers of Tay-Sachs, while sickle cell disease occurs in about 1 in 365 births among families of African ancestry in the U.S.
But belonging to one of these groups doesn’t mean you’ll definitely be a carrier; just that there’s a higher chance. Many people from these backgrounds choose to get tested to get a clearer picture of their own risks.
4. Health reasons
While most carriers of genetic conditions don’t experience symptoms, this isn’t always the case. Some can have mild health issues related to their condition. For example, some women who are symptomatic carriers of hemophilia experience abnormal bleeding even though they don’t have the condition.
A carrier test can offer an explanation and help you take steps to manage your health with more clarity and confidence.
Who should undergo carrier screening?
Source: Pavel Danilyuk
Carrier screening is often recommended for anyone planning to have children. Ideally, both partners are tested to get the clearest picture of potential risks.
Still, that’s how testing works in theory. In practice, it often happens one step at a time: one person gets tested first, and if they’re found to carry a condition, the other partner follows.
Of course, there are also exceptions. For certain conditions passed down through sex chromosomes, like hemophilia, testing is targeted. Hemophilia is carried on the X chromosome, so it’s typically women who are screened, since they can carry the gene without having symptoms. Men, with only one X, either have the condition or they don’t.
What does carrier screening test for?
Depending on the test you decide on, a carrier screening test can check for a variety of conditions. These typically range from common genetic conditions to those that are rare. Some of the most commonly tested conditions include:
Cystic fibrosis
Muscular dystrophy
Tay-Sachs disease
Thalassemia
Sickle cell disease
Spinal muscular atrophy
Hemophilia
The exact conditions included in the carrier screen depend on the type of test you choose. Some tests focus on specific conditions based on your family history or ethnicity, while others offer comprehensive panels that screen for hundreds of conditions at once.
What are the types of carrier screening for genetic conditions?
There are two main types of carrier tests you can opt for:
Targeted carrier screening
Expanded carrier screening
In the sections that follow, we’ll explain what each of these screening panels entails.
1. Targeted carrier screening
If you have a family history of a specific inherited condition, many healthcare providers recommend that you undergo targeted carrier testing. This screening method looks for specific gene variants related to a particular disease.
For example, if cystic fibrosis runs in your family, a targeted test may focus on the most common changes linked to your background. This can be more efficient because cystic fibrosis, for example, has over 1,000 known genetic variants, and not every test covers all of them.
Similarly, targeted testing is often used for illnesses linked to certain ethnic groups, like:
Sickle cell disease
Tay-Sachs disease
Beta-thalassemia
2. Expanded carrier screening
Expanded carrier testing is a broader approach to genetic screening. Instead of limiting the test to a few specific conditions or known genetic variants, it checks hundreds of genetic conditions simultaneously, regardless of ethnicity or family history.
This is particularly useful because many people are carriers of genetic conditions without knowing it, and it’s often difficult to know all the conditions that run in your family without taking a comprehensive carrier screening panel.
Bonus — If you’re interested in an expanded carrier screen, Nucleus Family screens for over 900 genetic conditions using advanced whole-genome sequencing (WGS) — one of the most accurate options available.
How is genetic carrier testing performed?
Source: Cottonbro Studio
To undergo a genetic carrier test, you’ll need to provide a DNA sample, which can be collected using three main methods: blood, cheek cells (buccal swab), or saliva. The table below outlines these testing methods and their level of invasiveness:
Testing method | Sample used | Degree of invasiveness |
|---|---|---|
Blood test | Blood draw | Minimally invasive |
Cheek swab | Buccal (cheek) cells | Non-invasive |
Saliva test | Saliva sample | Non-invasive |
The preparation for your genetic carrier screen largely depends on the type of sample you’re providing. If you’re taking a saliva or cheek swab test, you might need to avoid eating, drinking, or brushing your teeth beforehand to ensure accurate results.
Once your sample is collected, the provider sends it to a certified lab for analysis. The lab will test for known genetic variants based on the screening panel you’ve selected (e.g., expanded or targeted screening). After analysis, you’ll receive your results, which will tell you if you are a carrier for any of the conditions tested.
When should you do a carrier screening test?
Carrier genetic screening can be done at three key stages:
Before pregnancy
During pregnancy
After pregnancy
Ideally, carrier screening is done before pregnancy — often called preconception carrier screening. If you or your partner are carriers for the same condition, you can explore options like IVF with embryo testing or talk to a genetic counselor before trying to conceive.
However, if you didn’t do carrier screening before pregnancy, it’s not too late, even if you’re pregnant. Testing during the first trimester can still give you important insights — if the results show a higher risk, you’ll still have time to follow up with other prenatal tests, like NIPT or amniocentesis.
Some people also opt for carrier genetic screening after having one or more children. While this doesn’t provide as much time for planning, it can still offer valuable insights for future family decisions.
Understanding your results: What does a carrier test tell you?
Source: Cedric Fauntleroy
Carrier screening results are usually either positive (you’re a carrier of a specific condition) or negative (you’re unlikely to be a carrier).
A positive result means you carry a gene for a certain condition — and depending on your partner’s results, it could affect your child’s risk.
A negative result indicates there’s little to no chance you’re a carrier. Still, it doesn’t rule out the possibility completely, especially for conditions with rare variants that aren’t always included in a test panel.
So what happens if you’re a carrier? It depends on your partner’s results. Here’s a quick breakdown of what that could look like:
Parent 1 carrier status | Parent 2 carrier status | Possibility of the child being a carrier | Possibility of the child having the condition | Possibility of the child being unaffected |
|---|---|---|---|---|
Carrier | Non-carrier | 50% (1 in 2 children) | 0% | 50% (1 in 2 children) |
Carrier | Carrier | 50% (1 in 2 children) | 25% (1 in 4 children) | 25% (1 in 4 children) |
Non-carrier | Non-carrier | 0% | 0% | All children are unaffected by the condition |
It’s also possible (though less common) to receive a false positive or false negative. Although this can be unnecessarily stressful, repeating the test or doing a diagnostic one usually helps remove any uncertainties.
What do you do after getting your carrier screening result?
Receiving your carrier screening results can be a lot to process, but remember: their goal is to provide you with useful knowledge, not cause unnecessary worry. Depending on your results, here are a few paths you might consider:
Genetic counseling
IVF with preimplantation testing
Conduct prenatal diagnostic tests
1. Genetic counseling
A genetic counselor helps you understand the implications of your carrier status. They’ll explain your results in the context of your family’s health, clarify potential reproductive risks, and provide guidance on your options for family planning.
With their expertise, you’ll gain a clearer understanding of your options and what they mean for your future family.
2. IVF with preimplantation testing
If you’re considering other conception options due to your carrier status, IVF with preimplantation genetic diagnosis (PGD) can be a great option.
PGD allows doctors to test embryos for specific genetic conditions, so only those free of certain genetic issues are implanted. This can help reduce the risk of passing on inherited conditions and ensure your baby has the healthiest start possible.
3. Conduct prenatal diagnostic tests
If you got a positive carrier screening result and are pregnant, prenatal diagnostic tests (like amniocentesis and chorionic villus sampling) can confirm whether your baby has inherited the condition.
However, as these tests are invasive, you should discuss the potential risks with your healthcare provider before proceeding.
Bonus — Learn more about prenatal genetic tests:
How to choose the right genetic carrier screening test for you
Not all carrier screening tests are the same, and the right one for you depends on what matters most to your family. Here’s what to think about:
Scope of testing: If you’re only concerned about a condition that runs in your family, a targeted test might be enough. But if you want a broader picture of your risks, expanded screening would be better suited for you because it can check for hundreds of conditions at once.
Clarity of results: Some tests come with technical reports that could be hard for you to make sense of without your healthcare provider. If your results are sent directly to your doctor first, this might not be a big issue. But if you want to have a general idea of what the results indicate even before speaking to your doctor, it’s a good idea to choose a test that offers clear, easy-to-understand reports.
Cost: Many testing providers don’t provide upfront cost for their screening panels, which could mean you’d spend more than you’d expected on screening. As such, it’s always advisable to contact their billing department directly to get an estimate of how much you’d spend. Alternatively, you could opt for providers with more transparent pricing.
When comparing your options, remember that the best carrier screening test is the one that fits your needs — whether that’s broad coverage, clear results, or a simplified process. If you’re looking for a test that checks all those boxes, Nucleus Family is one worth exploring.
Considering expanded carrier screening? Meet Nucleus Family
Nucleus Family’s expanded carrier screening panel tests for over 900 genetic conditions, making it one of the most extensive options available. Plus, you don’t need a doctor’s appointment to take the test — Nucleus Family is physician-ordered and clinical grade.
Nucleus makes couples testing easy by syncing your results with your partner’s, giving you a clear picture of your combined genetic risk. You’ll receive a clear, easy-to-understand report that shows your carrier status and explains what it might mean for your pregnancy and family planning.
Once you receive your results, you can plan your next steps, whether using Nucleus AI for personalized recommendations or connecting with a genetic counselor through Nucleus’ partnership with SteadyMD.
Getting started with Nucleus Family’s carrier screening
Nucleus Family’s at-home carrier screening test is priced at $399 (partner screening, which includes two test kits, costs $798). This cost includes the test kit, two-way shipping, and detailed reports covering over 900 genetic conditions.
The test is non-invasive, using a simple cheek swab for easy and painless sample collection.
To get started:
Provide your personal details
Order your kit
In six to eight weeks, you’ll receive a detailed, easy-to-read report outlining your genetic carrier status.
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Featured image source: Antoni Shkraba
