What is carrier screening?

If you are pregnant or planning for pregnancy, carrier screening can help you understand your risk of passing on a genetic condition to your child.​

Carrier screening is a test that analyzes your DNA to see if you are a carrier of a genetic variant (or change) that could cause an inherited disease in your children. Medical experts, such as the American College of Obstetricians and Gynecologists, recommend that carrier screening be offered to all women who are pregnant or planning for pregnancy.​

What does it mean to be a carrier of a genetic condition?

​Every person has two copies of each gene. Carriers have one normal copy of a gene and one copy with a disease-causing variant (or change). Most carriers are healthy and do not have a family history of genetic conditions. There are two ways that a carrier may pass on a genetic condition to their child:

  • Autosomal recessive inheritance, when a child inherits a gene with a disease-causing variant (or change) from both the mother and the father​
  • X-linked inheritance, which typically occurs when a male inherits an X chromosome with a disease-causing variant from the mother


Sema4 Elements™ Expanded Carrier Screen tests for both autosomal recessive and X-linked diseases.

What are my options if I am a carrier?

If you are a carrier of a genetic condition, carrier screening may also be recommended for your reproductive partner. Our genetic counselors can help coordinate partner testing. If you and your partner are identified as a high-risk couple, your healthcare provider or genetic counselor can provide information and support to help you understand your reproductive options and make important family planning decisions.​​

Carrier screening plays an important role in family planning and is ideally performed before you get pregnant. This gives you the most reproductive options if you test positive as a carrier for a genetic condition. If you or your partner are already pregnant, carrier screening is still important to help you better understand your reproductive risk and prepare for a healthier future for your family.

If I am a carrier, what is the risk that my children will inherit the condition?

If both you and your reproductive partner are carriers of the same autosomal recessive condition, with each pregnancy you have a:​​​​

  • 1 in 4 (25%) chance of having a child affected with that disease​
  • 1 in 4 (25%) chance of having a child who is not affected by the disease and not a carrier​
  • 2 in 4 (50%) chance of having a child who is a carrier of the disease


If a woman is identified as a carrier of an X-linked condition, she has a 1 in 2 (50%) chance with each pregnancy to pass on the variant to her child. If a male child inherits the disease-causing variant, he will be affected with the X-linked condition.

If I receive a negative result, does that mean I have zero risk of being a carrier?

A negative result does not guarantee that you are not a carrier, due to the possibility of residual risk. Residual risk is your chance of being a carrier even though you received a negative result. It is based on your ancestry, as well as the ability of genetic testing technology to identify disease-causing variants in a particular gene.

Our Expanded Carrier Screen can identify ancestry information from your DNA, which is used to calculate the most accurate personalized residual risk. Based on your specific ancestry, Sema4 can determine how likely we are to detect disease-causing variants in a particular gene and provide you and your provider with your personalized residual risk information. Your specific ancestry information, however, is not visible to your provider.

Watch our Carrier Screening Pre-test Video

Your healthcare provider may have discussed the option of genetic carrier screening with you. The purpose of genetic carrier screening is to determine if a reproductive couple may be at increased risk of having a child affected with a genetic condition. Watch this informational video to learn more about genetics and the possible outcomes of carrier screening.

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