Ultimate Guide to Carrier Screening

Updated October 2, 2019

This article was scientifically reviewed by YourDNA

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What Is Carrier Screening?

Thanks to decades of genetics research and modern medical science breakthroughs, many people who believe they could have inherited a disease — or could potentially pass along a certain genetic mutation — can undergo carrier screening.

This form of genetic testing, also called a carrier screening panel, allows an individual or couple to determine if they carry genetic mutations that could be passed along to their children.

What's in this Guide?

Disclaimer: Before You Read

It is important to know that your genes are not your destiny. There are various environmental and genetic factors working together to shape you. No matter your genetic makeup, maintain ideal blood pressure and glucose levels, avoid harmful alcohol intake, exercise regularly, get regular sleep. And for goodness sake, don't smoke.

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Carrier screening for genetic conditions can also help people determine if they have a mutation that could lead to future health concerns and can be used to determine if a certain health condition runs in a family, even if some family members do not show symptoms.

Carrier screening for genetic conditions can also help people determine if they have a mutation that could lead to future health concerns and can be used to determine if a certain health condition runs in a family, even if some family members do not show symptoms.

What is a carrier?

Many people who hear about genetic disorders are confused about how someone can pass along a disease but not necessarily have the illness themselves; oftentimes, people only associate the term “carrier” to viral diseases, such as rabies.

So, what is a carrier of a disease?

A carrier is a person who has certain kinds of genetic mutations linked to a particular disease or health condition, and who may pass these mutations along to their children.

In many cases, carriers of genetic conditions unknowingly inherited these mutations from their parents, who also may be carriers who do not show any symptoms of the disease.

Some DNA carriers live their whole lives never knowing that they carry the genetic traits for certain kinds of diseases.

Yet other people may find out that they have a family history or genetic predisposition for certain health conditions only after they develop the disease, or their child or loved one does.

How Genetic Disorders Are Passed Down

Genetic disorders are often passed through families, from parent to child. But just because a parent is a carrier of a disease doesn’t mean their child will necessarily be a carrier or develop that condition.

That’s because half of your DNA comes from your mother, and the other half from your father, meaning that there’s a chance a genetic disorder isn’t passed along.

Each person has 46 chromosomes that are split into 23 pairs.

The first 22 of the pairs are called autosomal genes and they determine your eye color, hair color, and other features that make you who you are. The last pair of genes is what determines your gender.

Knowing this, researchers categorize genetic inheritance into three types based on how the disease is passed along:

  • Autosomal dominant genetic inheritance: With some diseases, only one copy of a mutated gene — from either the mother or father — needs to be passed along for a child to have the condition.
  • Autosomal recessive genetic inheritance: With other conditions, both parents must pass along a copy of the mutated gene for the child to have the condition.
  • Sex-linked genetic inheritance: Some genetic conditions only impact certain genders because of a mutation passed along with the chromosomes that determine gender.

The Chances of Having a Child With a Genetic Disorder

The chances of a child having a genetic disorder inherited from their parents greatly depends on the type of genetic disease and its inheritance pattern.

Genetic researchers believe that children of people who are carriers for autosomal dominant disorders have a 50 percent chance of developing an illness.

For health conditions that are autosomal recessive the odds decrease, but there remains the chance of becoming a carrier; in these cases, children have a 25 percent chance of developing the illness, a 25 percent chance of not having the illness and not being a carrier themselves, and a 50 percent chance of carrying the genetic mutation without any symptoms.

Disorders That Genetic Carrier Screening Test For

If you are considering having a universal carrier screening performed, you may be wondering just what illnesses and health conditions can be identified.

What does genetic carrier screening test for? Many genetic carrier screenings look for genetic mutations that cause a variety of illnesses, including:

  • Tay-Sachs disease
  •  Cystic fibrosis
  •  Fragile syndrome
  •  Sickle cell disease
  •  Down syndrome
  •  Hemophilia
  •  Duchenne muscular dystrophy
  •  Marfan syndrome
  •  Spinal muscular atrophy

Carrier Screening Tests Available

Carrier screening for genetic diseases can be tailored to each person who undergoes the tests. There are two main forms of screening: expanded carrier screening and targeted carrier screening.

These tests vary by the scope of disorders they test for based on risk factors such as family health history, being of a certain ethnicity, or having an unknown health history (which in particular can benefit adoptees who do not know their birth family’s medical health history).

Expanded Carrier Screening

With expanded carrier screening, a doctor will use one DNA sample to screen for a variety of disorders.

This kind of sampling isn’t hyperfocused on conditions that affect particular ethnic or regional groups.

With expanded carrier screening for genetic conditions, it’s possible for a doctor to explore whether or not you are a carrier for around 100 or more disorders.

Targeted Carrier Screening

Just as the name implies, targeted carrier screening is a more focused type of test that takes into account a person’s ethnicity, family health history, and other factors to determine what kinds of disorders to test for.

This kind of test usually examines a person’s DNA for fewer disorders, but those that are more likely to be inherited or passed along to future children.

If you’re unsure about which kind of screening would be best, your doctor will be able to determine your inherited risk factors.

From there, you can personalize a genetic screening to find out the information you need without testing for every kind of disorder possible, including those that you have a low risk of inheriting or passing along.

How Carrier Screening Works

Carrier screening is relatively easy to have performed. After speaking with a doctor to determine what level of carrier screening you need (expanded or targeted), your doctor will collect a DNA sample.

This sample can come through either blood or saliva, and the collection process usually takes just a few minutes.

From there, your DNA sample will be sent off to a laboratory — either one affiliated with your doctor’s office or one of the genetic carrier screening companies you and your doctor choose.

The lab will then analyze your DNA and look for mutations in your genetic code that are known mutations that can lead to a variety of health conditions.

The lab will then create a report for you and your doctor explaining if any mutations were found.

If you are choosing to undergo DNA testing with a spouse before having a child, both DNA samples will be analyzed, and the report you and your doctor received will explain the chances your child may have at developing a certain condition or being a carrier for a condition that may be caused by genetic mutations you have.

Many people who are waiting on results wonder, “how long does carrier screening take?” Generally, it’s possible to have test results back in as little as two weeks, but more complex tests that screen for a larger variety of genetic mutations may take as long as a month or more.

Why Is Carrier Screening So Important?

While carrier screening is becoming more and more popular, many people aren’t sure if they should pay for the testing to be done.

Is carrier screening necessary? You should know that it’s not. In fact, many people who do not have a family health history of inherited disease choose to forego carrier screening.

Still, many people find the cost of genetic carrier screening worth it, especially when they have a heightened risk of being a carrier for a particular condition.

Some carrier screening benefits include:

  • Knowing your child’s risk of developing a disease that is common in your family
  • Using carrier screening as a tool to rule out or diagnose a genetic condition that causes pregnancy difficulties, such as multiple miscarriages
  • Helping another family member with the diagnosis of a rare genetic disease that you may be a carrier of
  • Having a better understanding of genetic conditions you may be a carrier of or could pass along, and using that information during family planning

Carrier screening blood tests are a very personal medical procedure and choice — only you can determine if having the test performed is right for you.

When Can Carrier Screening Be Done?

Carrier screening can be done at any time, including during pregnancy. If you decide to have carrier screening done, there’s no need to worry about preparing for the test like you may need for other medical tests.

Your doctor will simply use a saliva or blood sample to collect your DNA.

Many people who consider carrier screening do so because they are considering starting a family.

Carrier screening before pregnancy is very common, especially for couples who have a family health history of certain conditions, or those who are planning to undergo IVF or fertility treatment.

Carrier screening in pregnancy is also the norm since it is commonly recommended during the first trimester.

Carrier screening and prenatal diagnosis is also an option; some pregnant women and couples choose to use carrier screening (with DNA collection through amniocentesis) to determine if their unborn child may have inherited a genetic condition.

This can be especially helpful for parents who need to prepare for a child with a particular health condition or use that information to make medical decisions during pregnancy.

Understanding Carrier Screening Results

Carrier screening results can be confusing to analyze because while they can tell you if you are definitively a carrier (or not) of a condition-linked disease, the results aren’t a guarantee that a future child will or won’t inherit the disease.

Many people confuse results of carrier screening and diagnosis of a particular disease, when in fact it is possible to be a carrier who has children who do not develop the condition or who will even be carriers of the gene mutation.

If you choose to undergo carrier screening, meeting with a doctor or genetic counselor to explore your carrier screening results can ensure you understand the results and how to move forward with that information.

Accuracy of Carrier Screening Tests

You should know that for the most part, carrier screening tests are highly accurate.

Still, there is always the chance to have a false-negative (which would suggest that no genetic mutation is present) or a false-positive (which would suggest that you are a carrier of a genetic mutation linked to a particular disease).

As DNA analysis technology progresses and becomes more accurate, the chances of having an inaccurate test are less and less.

Costs of Carrier Screening

The costs of carrier screening can vary from person to person thanks to a wide range of insurance coverage plans and the number of genetic screens performed.

According to the National Institutes of Health (NIH), genetic testing can cost anywhere between $100 and $2,000.

Less complex tests, such as simple one-panel carrier testing and newborn screening are often on the lower end of the cost scale, while tests that involve multiple family members and larger test panels can be more pricey.

Is carrier testing covered by insurance?

Carrier screening test costs can often be lowered by insurance if your plan chooses to cover it.

In some cases, your doctor may need to explain to your insurance provider why the test is necessary in order to have the screening covered.

Who Should Receive A Carrier Screening?

According to the American College of Obstetricians and Gynecologists, carrier screening is recommended to many women who are pregnant (and their partners) or thinking about starting a family.

But that doesn’t mean everyone has carrier screening performed or needs to have it done.

In addition, there are benefits to having a carrier screening people who don’t plan on having children. You may want to have a carrier screening test if:

  • You have a family history of an inherited condition
  • You are a part of an ethnic group that has a high risk of a certain condition, for example, Tay-Sachs disease is more prevalent among people of European and European Jewish descent while cystic fibrosis is more common in people of Northern European descent
  • You already have children who may be exhibiting symptoms of an inherited disorder
  • A family member has been diagnosed with a disorder that may be genetic, and having a carrier screening performed may help offer medical clues that support their diagnosis

Speaking with a doctor and weighing your options is the best way to determine if you should have a carrier screening test performed.

What Happens If I Am A Carrier?

Finding out that you are a carrier for a genetic health condition can be shocking to hear — and it can also be scary.

You should know that many people who are carriers of genetic conditions never develop the disease themselves, and often go on to have children who do not have the disease, either.

Finding out you are a carrier can actually calm some fears and help you make future medical decisions, especially if you are planning to have children.

What if my partner and I are both carriers for the same genetic disorder?

Finding out that you and your partner are both carriers for the same condition doesn’t mean that you won’t be able to have children.

For example, being a carrier for cystic fibrosis and pregnancy aren’t incompatible — many people who are carriers of the disease seek out other genetic testing and fertility treatment options (such as IVF or surrogacy) so that they can have healthy children who don’t develop the disease.

Getting help with genetic counseling before pregnancy can help you both make informed decisions that lead to a healthy child, and can quell fears about having children who have the disease or who are carriers of the gene mutation.

Genetic carrier screening is a great tool that gives you information you can use for a variety of medical and health purposes, should you choose to have the test performed.

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