Genetic screening for pregnant women and people planning a family can reveal potential risk for certain inherited diseases.
Most babies born with a genetic condition do not have a family history of that disease. Genetic screenings, done with a blood test, are now available to determine if you and your partner have an increased risk of having a child with one of hundreds of inherited genetic diseases.
This test is called universal carrier screening.
What is universal carrier screening?
Universal carrier screening looks at many genes – instructions – in our bodies for the most common ways these genes might be damaged, like having a misspelling in the instructions. Misspellings in a gene can cause them not to work correctly.
If a person has one working copy of a gene and one misspelled gene, that person will be a carrier of a genetic disease, but will not show signs of the disease. Some diseases affect only males because they have only one copy of each gene, while females have two copies.
What types of diseases does universal carrier screening look for?
Universal carrier screening determines your risk of having a child with an early-onset disease (for example, cystic fibrosis, sickle cell anemia, spinal muscular atrophy, and Tay Sachs disease). These diseases may involve significant medical management, intellectual disability and costly medical treatments. A few genetic diseases are “life-limiting,” meaning that children born with one of these conditions often die before age 10.
What if both parents are carriers?
Parents who are carriers of the same genetic condition each have one non-working copy of a gene and one working copy. These parents have a 1 in 4 chance (25 percent) with each pregnancy to pass on two non-working copies of the gene. Children with two non-working copies of a gene will have the disease. These couples have the option to elect testing during or after the pregnancy to learn whether the baby has the disease.
What happens if my test results show that I am a carrier?
Patients who are found to be carriers will be referred to a genetic counselor to review the results. You and your partner will be offered additional tests to find out more about your risks during pregnancy and your baby’s risk for the genetic condition.
What do the results mean?
A “normal” result is good news. Normal indicates a very low chance you are a carrier of the genetic diseases that were tested. However, the test is not perfect and may not identify all carriers.
Why should I have this testing?
Results from a universal carrier screening test can give you information about your risks of having a baby with certain genetic diseases. Some couples find this information helpful for family planning.
Is there a reason not to have this testing?
Not all couples value the information that is provided through universal carrier screening. For that reason, the results can cause unwanted anxiety during the pregnancy.
Universal carrier screening does not screen for all genetic conditions. Patients with concerns about a family history of a specific condition or those who desire more genetic information about a current or future pregnancy should meet with a reproductive genetic counselor.
Vanderbilt has four reproductive genetic counselors who counsel all patients who want universal carrier screening or more information about their reproductive risks and screening options.
There are also prenatal genetic tests that can be done to check a fetus for possible congenital problems. Also, in Tennessee, babies are screened for many potentially serious health conditions soon after birth.
This post was written by four Vanderbilt genetic counselors: Jill Slamon, MAT, M.S., LCGC; Caitlin Grabarits, MGC, LCGC; Randa Newman, M.S., LCGC; and Martha Dudek, M.S., LCGC.