Genetic carrier screening is a blood test that evaluates your DNA to see if you are a “carrier” for any one of a few hundred inherited diseases.
In order to determine if this test is something you are interested in, here is a brief overview of genetic carrier screening, and what patients can do after receiving the results of their tests.
If you’d like more information about genetic testing, Genetic counseling is available through Maternal Fetal Medicine Associates.
Your DNA is composed of 23 pairs of chromosomes, which provide the basis for how your body develops, grows, and functions. During the process of cellular replication, sometimes the DNA becomes altered in ways that can become detrimental, either to yourself or your offspring. These alterations, known as “pathogenic variants,” can ultimately causes three types of conditions:
- Autosomal recessive condition: this occurs when a person inherits two non-working copies of the gene. Carriers for autosomal recessive conditions have one mutated gene and one normal gene, which means they are not affected by the condition. However, if both parents are carriers, each of their offspring has a 25% of actually having the condition.
- X-Linked condition: this occurs when there are DNA changes on an X chromosome, of which women usually have two and men usually have one. Thus, male children are more commonly affected by these disorders, as they do not have a second normal gene.
- Autosomal dominant condition: this occurs when a person inherits a non-working copy of the gene, which overrules the normal second copy. These individuals have a 50% chance of having a child who is also affected, even if their partner has two normal genes.
It is most likely that you will be found to be a carrier for some sort of genetic condition, as 80% of people are. Since most people are unaffected by their carrier status, they are usually unaware of their genetic makeup. However, carrier screening can be beneficial when planning to have a family, as it may identify a risk of having a child who will be affected by a serious disease. Furthermore, it can also be useful information for your siblings or other close relatives, as they may share some of your genetic makeup.
If you are found to be a carrier for a genetic condition, the first step is to test the DNA of your partner or donor sperm, if applicable. Then, if the second test results show that you are both carriers for the same genetic condition, there are several reproductive options you can pursue.
Some patients decide to move forward as they normally would, understanding the risk that their child may have a genetic condition. However, some patients decide to pursue options to reduce the risk of their child having a genetic condition. One such option is IVF, or in vitro fertilization, with pre-implantation genetic testing. This involves testing the genetics of the embryo before transferring it to the uterus (and subsequently avoiding implantation of affected embryos). Others decide to pursue egg or sperm donation, or to choose adoption instead of trying to become pregnant at all.
If you are already pregnant before receiving the results of your genetic carrier screening and find that you are at risk of having an affected baby, you may choose to have a CVS or Amniocentesis done. These tests directly evaluate the fetal DNA and will allow for diagnosis of the genetic condition, if present.
To schedule an appointment with a genetic counselor, call Maternal Fetal Medicine Associates at (212) 235-1335 or request your appointment online.