Genetic Carrier Screening
We have two copies of every gene. A carrier is an individual who has inherited a mutation in one, but not both, of those copies. The copy without a mutation serves as a “back-up” and the carrier usually shows no problems from the mutation. If an individual has a mutation in both copies of the gene, then s/he will most likely show signs of the condition and is considered to be affected with the genetic condition. This phenomenon of carrier and affected individuals is known as autosomal recessive inheritance.
Most people do not know they are a carrier for a genetic condition because they do not have any symptoms from just being a carrier. However, if both parents are unknowingly carriers for the same genetic condition, they may each pass on their copy of the gene with the mutation and have a child who is affected with the condition. If both parents are carriers, the likelihood of this happening is ¼ (25%) with each pregnancy. Carrier screening is a method of testing one or more genes to determine if one or both parents carry a mutation and are therefore at-risk of having a child affected with a genetic condition. The type of carrier screening offered is based on family history, ethnic background, or patient request.
Carrier screening is generally performed via a blood test, although some carrier tests are available via a saliva test. If one parent is found to be a carrier for a genetic condition, testing for the other parent is then indicated. Most carrier testing can reduce your risk to be a carrier for a genetic condition, but cannot eliminate it.
All carrier screening tests are available at the Center for Fetal Medicine. We routinely test for many conditions, including but not limited to: cystic fibrosis, sickle cell disease, thalassemia, Tay-Sachs disease, fragile X syndrome, and spinal muscular atrophy.
For those who wish to be tested for a large number of conditions at once, we offer cell-free DNA testing otherwise known as non-invasive prenatal screening. This screening test can evaluate your carrier status for 90 different recessive disorders. To learn more about carrier screening options, please visit www.mytestingoptions.com
Ideally carrier screening should take place before conception so you are aware of your risks and can discuss your options with a genetic counselor. If you are already pregnant and have carrier screening that shows you and your partner are both carriers of the same genetic condition, you may opt for diagnostic testing, such as CVS or amniocentesis to determine if the fetus is affected.