What is genetic carrier screening?
Genetic carrier screening is a form of genetic testing. The screening determines if either parent has the genetic predisposal for specific diseases. The testing consists of blood work, saliva, and tissue samples. Tests are either positive or negative. Fortunately, there is no middle ground. Either the parents are carriers of certain genes or not. The parent likely to be the carrier is tested first. If the parent tests positive, the additional parent will be tested as well. Genetic carrier testing only needs to occur once. If the parents tested negative or positive before, the test result will not change in the future.
Types of screening
There are 2 types of genetic carrier testing. Screening pre-pregnancy allows doctors to determine the likelihood that the baby will develop a certain disease. Diagnostic testing is performed during the pregnancy. The test informs the parents if the fetus has already developed the specified disorder.
What is a genetic carrier?
A genetic carrier is an individual that carries a recessive gene for a specific disease. The individual may have mild to no symptoms at all. Often, the individual is unaware of the genetic predisposition. Some diseases require the mutated gene from both parents and other diseases require the gene from only one parent. There is only a 25% chance that both parents will be carriers of the same disease. When both parents are carriers, the children have a 25% chance of not inheriting the gene, a 50% of carrying the gene but remaining unaffected, and a 25% chance of carrying the gene and developing the disease.
When is the right time for genetic carrier screening?
There is no right or wrong answer. Genetic carrier screening is available to all people. Individuals with a family history of specific disorders should get tested when starting family planning. Certain ethnic groups are also more likely to get specific diseases. The most common diseases that will be tested for include cancer, cystic fibrosis, sickle cell anemia, Tay-Sachs disease, muscular dystrophy, and fragile X syndrome (FXS).
Screening during IVF
Genetic carrier screening can be part of the IVF process. When determining a sperm or egg donor, selecting a donor free of certain diseases will give the child a healthier future. Even if the sperm and egg from the parents will be used, screening for mutated genes can ensure a healthy pregnancy. Certain diseases can affect the embryo and potentially result in miscarriage.
Anyone seeking to eliminate the possibility of passing on genetic predispositions to specific diseases should get tested. The test is a combination of blood work, saliva, and cheek tissue samples. Once the test is done, screening does not need to be repeated in the future, even for multiple pregnancies. Couples who are interested in genetic screening as part of IVF treatment should consult with a healthcare provider or fertility specialist to learn more.