Genetic carrier screening tests a person’s DNA to determine if they are at increased risk to have a child with certain genetic conditions. We all carry changes called variants in our genes that can cause genetic conditions. Thankfully, most of these variants will never affect our own health or the health of our children.
Genetic carrier screening evaluates for conditions that are inherited in either an autosomal recessive or X-linked manner. For conditions that are autosomal recessive, both the person contributing the egg and the person contributing the sperm must carry variants in the same gene in order to have a child who is affected with that condition. Common examples of autosomal recessive conditions would be cystic fibrosis, spinal muscular atrophy, sickle cell disease, or Tay-Sachs disease. Carriers for X-linked conditions who are contributing their eggs have an increased chance to have a child who is affected with that condition. Since healthy individuals with XY chromosomes (e.g. most cisgender males and transgender females) are not typically at risk for having children affected by X-linked conditions, many labs do not screen them for X-linked genes. Common examples of X-linked conditions would be Fragile X syndrome or Duchenne muscular dystrophy.
Since being a carrier for one or more genetic conditions is very common, anyone who is pregnant or planning to become pregnant should consider having genetic carrier screening. The results can provide you with important information about your chances to have a child with certain genetic conditions. If your results indicate you are at increased risk to have a child with a genetic condition, you will have the opportunity to discuss your reproductive options with your physician (see question 13).
Yes. In fact, genetic carrier screening was specifically designed to screen for genetic conditions that are unlikely to be detected due to a family history. Even if you have other children who are healthy, this cannot rule out the possibility you and/or your partner could be carriers for a genetic condition.
There are many options for genetic carrier screening. Some screen for only a few conditions, while others screen for hundreds of conditions. There is not one right answer for everyone. The conditions you are screened for depends on your personal preferences and the advice of your physician. Your ancestry may also play a role in determining which conditions you should be screened for since certain genetic conditions are more common in specific populations. Keep in mind: the more conditions you screen for, the more likely it is you will be a carrier for one or more of them.
The American College of Obstetricians and Gynecologists (ACOG) and the American College of Medical Genetics (ACMG) have published guidelines on genetic carrier screening. ACOG recommends carrier screening for cystic fibrosis and spinal muscular atrophy be offered to all individuals who are pregnant or planning to become pregnant. ACOG recommends carrier screening for Fragile X syndrome be offered to individuals with XX chromosomes (e.g. most cisgender females and transgender men) with a personal or family history of Fragile X-related disorders, intellectual disability, unexplained ovarian insufficiency, or an elevated FSH level before age 40. ACOG recommends screening for certain blood conditions including alpha thalassemia, beta thalassemia, and sickle cell anemia be offered to those at increased risk based on their ancestry (e.g. African, Mediterranean, Middle Eastern, Southeast Asian, or West Indian). Finally, ACOG recommends carrier screening for cystic fibrosis, Canavan disease, familial dysautonomia, and Tay-Sachs disease be offered to all Ashkenazi Jewish individuals. Very recently, ACMG updated their guidelines to advocate for screening all individuals for a more broad panel of genetic conditions (sometimes referred to as expanded carrier screening) regardless of their ancestry.
Ideally, genetic carrier screening should be completed prior to pregnancy or the start of fertility treatment (e.g. an IUI or IVF cycle). This allows your physician or genetic counselor to offer you the most reproductive options in the event you are at increased risk to have a child with a genetic condition (see question 13).
You and your partner are welcome to be tested at the same time, but this is not required. Often the individual contributing their eggs will be tested first. If their genetic carrier screening is normal, the individual contributing their sperm does not need to undergo testing. If their results are abnormal, we will recommend the other partner be tested next. Testing both partners at the same time is another approach and may be right for you if the wait time for results is a concern. If you are tested together, both results will be available around the same time and can be faster overall (see question 18).
It is important to keep in mind there are limitations when working with eggs or sperm from a non-directed (previously called anonymous) donor. Many donors have had some form of genetic carrier screening that will be part of their profile, but the number of conditions tested can vary widely. If your donor is a carrier for one or more autosomal recessive condition(s), we would strongly recommend the other individual contributing eggs or sperm have genetic carrier screening for the same condition(s) before committing to that donor.
If your donor’s genetic carrier screening was normal, the question is more complicated. If you undergo genetic carrier screening that includes conditions for which your donor was not tested, you may find out you are a carrier for a condition that we do not have information on for the donor. Requesting additional testing on a donor can be time-consuming, costly, and may not be feasible if the donor is unreachable or does not consent to additional testing. Therefore, we recommend you discuss your options carefully with your physician or genetic counselor prior to having genetic carrier screening.
Not necessarily. If you have a family history of a specific genetic condition, it is important to meet with our genetic counselor to review your case. A genetic counselor can recommend the best genetic test to ensure you get the information you need to understand how your family history might affect you and your future child(ren).
In general, the same genetic test does not need to be performed twice as the results are not expected to change. However, there are many different types of genetic tests, and the technology is improving rapidly so it cannot be assumed your previous genetic testing is the same as the current options we offer. Please ensure our office receives copies of any previous genetic testing you have had. Your physician or genetic counselor can review the results to determine if any additional genetic testing may be beneficial for you.
Most of the genetic conditions included on genetic carrier screening are rare. However, when you are screened for many conditions at once, it is quite common to learn you are a carrier for one or more of them. The more conditions you are screened for, the higher the chance you will be a carrier for at least one. Our current recommendation for genetic carrier screening evaluates for 274 conditions, and approximately ~70% (7 in 10) individuals will learn they are a carrier for at least one condition.
Typically not, but there are exceptions. You have two copies of most genes: one copy inherited from each of your biological parents. Carriers have one non-working copy of a gene, but their other copy is functioning normally. As a result, carriers for recessive conditions do not typically exhibit any symptoms. However, being a carrier for certain conditions may elevate a person’s risk for specific health issues. When we return your results, we will notify you if there are any known implications for your own health that require follow-up.
If the person contributing the eggs and the person contributing the sperm are both carriers for the same autosomal recessive condition, there is a 1 in 4 (25%) chance of having a child affected with that condition with each pregnancy. There is a 2 in 4 (50%) chance of having a child who is a carrier, but who is typically not affected with that condition. Finally, there is a 1 in 4 (25%) chance of having a child who is neither affected by nor a carrier for the condition.
If the person contributing their eggs for a pregnancy is identified as a carrier of an X-linked condition, they have a 1 in 2 (50%) chance to pass on that variant in each of their eggs. If the child has XY chromosomes (most commonly, a male child), the child will be affected with that condition. If the child has XX chromosomes (most commonly, a female child), the child may be mildly affected or an asymptomatic carrier. More rarely, an individual with XX chromosomes may have symptoms that are equally severe to an individual with XY chromosomes with the condition.
If you are at increased risk to have a child with a genetic condition, the results can help you plan and prepare. Your physician or genetic counselor can review all of your available reproductive options to help you make the choice that is best for you.
Patients who undergo IVF may choose to have preimplantation genetic testing (PGT), a process used to test embryos for a specific genetic condition. PGT allows your physician to select and transfer only embryos which are not expected to be affected by the condition. If IVF with PGT is not right for you, genetic testing can also be performed during pregnancy through either chorionic villus sampling (CVS) in the first trimester or amniocentesis in the second trimester. CVS and amniocentesis both provide highly accurate genetic test results for the fetus allowing you to know if the condition was inherited or not. The results may be important for pregnancy management or medical planning for the birth of an affected child. Finally, some patients choose to use an egg or sperm donor who is not a carrier for the same condition in order to greatly reduce the chances of having an affected child.
No. Genetic carrier screening assesses your risk to have a child with a select number of genetic conditions. A normal result greatly reduces the risk your future child(ren) could be affected by those specific conditions, but it cannot eliminate the risk entirely. The small remaining risk is mainly due to the possibility there may be variants in your genes that can cause disease, but which are not able to be detected with our current knowledge and technology. No genetic test is perfect.
It is also important to remember every pregnancy has a background risk of approximately 3%-5% to result in a child with a birth defect or genetic condition. This risk is always present, regardless of the screening performed.
There are a few things to consider. First, there is a cost associated with genetic carrier screening, which may result in an out-of-pocket expense even with insurance. Second, results take approximately two to three weeks to return. The wait can be frustrating or anxiety-provoking for some patients. Ideally we like the results to be complete before you start an IVF or IUI cycle. Third, some individuals do not want the type of information provided by genetic carrier screening. For some, the information would cause anxiety. For others, they know they would not change their family building plans and would not pursue genetic testing of their embryos or pregnancy despite any results from genetic carrier screening. However, patients who feel this way may still find the information from genetic carrier screening useful in preparing for the potential birth of an affected child and arranging testing for their child after birth. Fourth, genetic carrier screening cannot entirely eliminate the risk for genetic conditions in your future children (see question 14). Finally, although rare, genetic carrier screening may identify a genetic variant that has implications for your own health (see question 11). Patients may experience distress if their results indicate they have an increased risk to develop a health issue.
Many insurance plans provide coverage for genetic carrier screening, but specific benefits must be checked for each patient. The labs we work with can check your insurance benefits on your behalf and offer you reduced self-pay pricing (typically in the range of $200 – $350 per person) if genetic carrier screening is not covered by your insurance plan.
A small blood sample (1-2 teaspoons) is the best sample for genetic testing and will be drawn in our office. In rare cases, we may submit a saliva sample instead of blood, but this is not preferred.
Results of genetic carrier screening typically take two to three weeks from the time your sample is received by the laboratory.
Our office will contact you by phone or the patient portal (MyChart) once your results are available. Typically, our genetic counselor returns all genetic carrier screening results so she can assist with any questions you may have at that time. We will also provide you with an electronic copy of your results via MyChart for your records.
Any genetic variants you are found to carry are likely to be inherited. When someone is a carrier for a genetic condition, it was most often inherited from one of their biological parents. Your full siblings typically have a 50% (1 in 2) chance of being a carrier for the same genetic condition(s) as you. More distant relatives such as aunts, uncles, and cousins would also be at increased risk to be carriers. For this reason, we strongly encourage you to share your results with your family. If you need help explaining your results to your family, our genetic counselor will be happy to assist.
If your genetic carrier screening is normal, your results do not rule out the possibility another family member (such as a sibling) could be a carrier for those genetic conditions. Your family members should still have their own genetic carrier screening performed if desired.
A positive (abnormal) result is highly accurate. False positives are very rare in genetic carrier screening. A negative (normal) result cannot completely eliminate the possibility you are a carrier for the conditions tested, but it does greatly reduce your risks (see question 14).
We strongly encourage all patients or couples who have high-risk genetic carrier screening results to have an appointment with our genetic counselor. This consultation will ensure you fully understand the implications of your genetic test results, how your future child(ren) may be impacted by any conditions for which they are at risk, and your full range of reproductive options. Our genetic counselor will also determine if there are any additional recommendations based on your test results or family history. The goal of genetic counseling is to provide accurate, balanced information and support the decision-making process of the patient.