If abnormalities are discovered during your prenatal screening or there is a family history of certain conditions, you will probably be recommended for genetic counseling as well as more extensive medical testing. Genetic counseling allows you to work one-on-one with a health care professional who has training and expertise in genetic health risks, conditions and testing options. It is especially important to consider genetic counseling if either partner has a genetic disorder, you have a child with a genetic disorder, a genetic disorder exists in the family or your ethnic background has a high proportion of carriers of a disorder. Your counselor can offer support and help you comprehend the results of your tests.
A genetic counselor will require as extensive a health history as possible for both parents and members of their families. You will be asked to discuss your own health and that of relatives. The ethnic background of both parents will also be explored, as some disorders are much more prevalent in particular ethnic groups. This will help the counselor create an overview of certain inheritable risks your children could potentially face. The counselor can also assist you in understanding the likelihood of a genetic condition appearing due to personal or family health issues.
Carriers are individuals who have inherited one gene for a particular condition, but not a pair. When a person has a pair, inherited from both parents, the condition is present. But if only one gene has the trait, there are usually no symptoms of the disease. That person would most likely never even know they are a carrier unless testing is performed. However, these recessive disorders can appear in a child when both parents were unknowingly carriers. The chances are one in four of a child receiving both defective genes and inheriting the disease if both parents are carriers.
Carrier screening is DNA testing to determine whether a couple are carriers of the trait for certain conditions and therefore are at risk for having a baby with the disease. The testing performed will focus on your particular family history and ethnic background, based on what conditions are more frequently found among that group. For example, those of Ashkenazi Jewish ancestry will often have a panel that focuses on the four most common recessive diseases among that group: Tay-Sachs, canavan, cystic fibrosis and familial dysautonomia.
The screening should take place before conception so you are aware of your risks and can weigh your options with a genetic counselor. If you are already pregnant and have a carrier screening that shows you and your partner are both carriers of a condition, you may opt for diagnostic testing of the fetus such as an amniocentesis or CVS to find out whether two copies of the defective genes are present.
Carrier screening is performed through a blood or saliva test. One sample can be tested in the laboratory for numerous diseases. If one partner is found to be positive for a trait, the other will then be tested. It is not necessary to test the second partner if the first tests negative because copies of the gene mutation must be present in both parents to pass along these traits.
All carrier screening tests are available at Maternal Fetal Care P.C. We routinely test for many common diseases, including:
- Cystic fibrosis
- Sickle cell disease
- Familial dysautonomia
- Canavan disease
- Fragile X syndrome
- Gaucher disease
- Mucolipidosis IV
- Niemann-Pick disease type A
- Fanconi anemia group C
- Bloom syndrome
Since many people do not belong to a single ethnic group, we offer the Inheritest Carrier Screen for a comprehensive option to cover many possibilities. This screening test will gather your genetic information to evaluate for more than 90 recessive disorders.
Another important form of carrier screening we provide at Maternal Fetal Care P.C. is specific testing for Trisomy 21, the most common cause of Down syndrome. The most frequently occurring chromosomal variation, Down syndrome is found in approximately one out of every 800 infants. Aside from family history, the age of the potential parents can be a factor. In other patients, it is just a random genetic deviation. We offer the MaterniT21 Plus test to help analyze a patient's risk.