Reproductive Health
What is carrier screening?
Carrier screening can give you important information about your chances of passing on a serious genetic condition to your children
Carrier screening is for individuals or couples who are planning a pregnancy or are currently pregnant. The purpose of carrier screening is to identify individuals who are at risk to have a child with a serious genetic condition.
Genetic conditions included have a range of symptoms, and some can be life-threatening. Some recessive condition can be managed with a special diet, while others can lead to developmental delays and intellectual disability. Some conditions are life-threatening or life-limiting, leading to death in childhood.
Carriers are usually healthy and have no family history of the genetic condition
3 out of 4 people are carriers for at least one recessive genetic condition
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Most people do not know they are a carrier of a genetic condition until they have an affected child
What conditions are included on carrier screening?
Two types of inherited genetic conditions are included on carrier screening. They are called recessive and X-linked conditions. Carrier screening can screen for hundreds of genetic conditions in one test.
Recessive Conditions
We have two copies of most genes in our bodies. We get one copy from our mother and the other from our father. Recessive conditions occur when both copies of the gene are not functioning correctly. Individuals who have one working copy and one non-functional copy are called carriers. Carriers typically do not have any symptoms of the disease.
When both parents are carriers for the same genetic condition, the couple has a 25% chance of having a child with that condition in each pregnancy.
X-Linked Conditions
Biological sex is determined by the sex chromosomes. Females typically have two copies of the X chromosome, and males have one X and one Y chromosome. X-linked conditions are caused by mutations in genes located on the X chromosome. Females are carriers of an X-linked condition when they have one non-functional copy and one working copy of a gene located on the X chromosome. If a male inherits the non-functional copy of the gene, they are typically affected since they only have one copy of the X chromosome.
Females who are carriers of an X-linked condition are at risk to have a child affected with the condition. This risk depends on the sex of the offspring. For male children, there is a 50% chance that the child would be affected with the condition. For female children, there is a 50% chance that they will be a carrier of the condition.
What are the benefits of carrier screening?
Individuals or couples may choose to get information on their carrier status for a variety of reasons. Learning this information prior to conception gives couples the most options if both partners are carriers for the same inherited condition. According to the American College of Obstetricians and Gynecologists, the ideal time to have carrier screening is before a pregnancy.
By doing carrier screening prior to conception, couples can make informed reproductive decisions. Options include:
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Conceiving naturally
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Option to test the fetus during pregnancy to determine if affected
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Test child after they are born to determine if affected
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Conceive using in vitro fertilization (IVF) with pre-implantation genetic diagnosis (PGD)
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IVF with PGD allows couples to only implant embryos that are not affected
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Use donor egg or sperm
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Adoption
By doing carrier screening during pregnancy, couples can make informed decisions for themselves and their families:
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Option to have diagnostic testing, including CVS or amniocentesis, performed on the pregnancy to determine if affected or to test after the baby is born
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Meet with specialists to plan for delivery
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Prepare medically and emotionally for a baby with a genetic condition
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