Genetic carrier screening is a genetic test that tells individuals whether they carry a specific genetic mutation associated with a certain genetic condition. For example, Huntington’s disease, a condition that causes deterioration the nervous system, can occur in an individual who inherits one copy of the mutated gene (this is known as a dominant genetic disorder). Other conditions, like sickle cell anemia, require that the individual inherits two copies of the mutated gene (this is known as a recessive genetic disorder). Genetic carrier screening tests specifically for genetic mutations associated with recessive genetic disorders. 

What is a Genetic Carrier? 

A genetic carrier is an individual who has inherited one copy of a mutated gene associated with a recessive genetic disorder. Carrying one copy will not cause signs or symptoms of the genetic condition to occur, but this individual is at risk of passing the gene onto his/her children. Genetic carrier screening relies on a powerful technique called Target Enrichment, a method that significantly improves the accuracy of genetic testing. This technology allows scientists to focus on specific regions of the genome known to harbor mutations associated with genetic disorders. Honing in on these relevant areas streamlines the testing process and delivers more accurate results. The results of a genetic carrier screening provide many benefits to individuals. Some of these benefits are explained below.  

To Obtain Information Regarding a Current Pregnancy and Future Pregnancies

Genetic carrier screening can be performed during pregnancy, as it only requires a blood draw, to provide information regarding the health of the baby. If you test positive as a carrier for a certain condition, and your partner tests negative for the same disorder, then your child has a zero percent chance of inheriting the disorder. If you and your partner test positive as carriers for the same genetic mutation, your child has a 25 percent risk of inherited the disorder. In this case, your obstetrician will closely monitor the health of your baby, paying special attention to watch for signs of a genetic disorder. In addition, there is a 50 percent chance that your child will be a carrier. These risks are the same for each and every pregnancy and do not change with subsequent pregnancies. 

To Develop a Pregnancy Plan

Genetic carrier screening can also be performed before pregnancy. If an individual and their partner get genetic carrier screening before pregnancy and are carriers of the same genetic condition, they will have the option to explore fertility options. For couples who are at a higher risk of having a child with an inherited genetic disorder, fertility options include:

• Natural pregnancy: Couples can decide to have a natural conception pregnancy. In the second trimester of pregnancy, if requested by the couple, diagnostic procedures can be performed to test the DNA of the child. In addition, chromosomal testing can be performed on the baby at birth (using a blood draw) to determine if the child has inherited the genetic condition.

• In vitro fertilization (IVF): IVF is a conception method that involves fertilizing eggs and sperm in a laboratory. Both the egg and sperm from the couple can be used, or donor eggs and/or sperm can be used. Artificial fertilization allows technicians to choose fertilized eggs free from genetic mutations associated with genetic disorders. This is done by performing preimplantation genetic diagnosis.

• Adoption: Some couples choose not to undergo the risk of possibly having a child with a genetic disorder. In this case, couples consult private or government adoption agencies to begin the adoption process. 

Consider Working with a Genetic Counselor

Ideally, individuals and couples who want genetic carrier screening work with a genetic counselor. Working with a genetic counselor will ensure individuals that they are receiving accurate information regarding genetic carrier screening and their results, enabling individuals to make informed decisions regarding family planning.

SOURCES:

https://ghr.nlm.nih.gov/primer/testing/benefits

https://www.centogene.com/genetic-testing/benefits-of-genetic-testing.html

http://www.lawrenceobgyn.com/pdf/genetic-carrier-screening-consent-w-chart-040316.pdf

https://www.acog.org/Patients/FAQs/Carrier-Screening

https://www.mayoclinic.org/autosomal-recessive-inheritance-pattern/img-20007457

https://genetics.emory.edu/documents/resources/Emory_Human_Genetics_Reproductive_Options.PDF