Genetic disorders are often conditions caused by a mutation on a specific gene, resulting in certain symptoms or physical manifestations. The majority of inherited genetic disorders are called autosomal recessive disorders. This means that two copies of an abnormal recessive gene were inherited, activating the disorder.
A recessive gene needs to be inherited with another recessive gene in order to exhibit physical traits. What happens if an individual inherits an abnormal recessive gene and a healthy dominant gene? The dominant gene will take precedence, even if the recessive gene is abnormal.
What Is a Carrier?
A carrier is a healthy man or a healthy woman who has a mutation on a specific recessive gene, which can lead to the presence of a genetic disorder. However, these individuals do not show signs or symptoms of a genetic disorder because they also have a dominant, healthy copy of the gene. Although these individuals are not at risk of developing a genetic disorder, they do have the possibility of passing on the mutated recessive gene to their children.
Who Is At Risk of Being a Carrier?
Certain individuals have an increased risk of being a carrier. These individuals include those who:
- have a genetic disorder
- have a child with a genetic disorder
- have a family history of a genetic disorder
- belong to an ethnic group that has a high rate of carriers of a certain genetic disorder
If both parents are carriers, there is a 25% chance that both parents pass on the recessive gene to their child so that the child inherits the disorder. However there is a 50% chance that one parent passes on a recessive gene and the other passes on a dominant healthy gene. In that case, the child will be a carrier for the genetic disorder.
If only one parent is a carrier, there is a 0% chance that the child will be born with the genetic disorder. The parent who is carrying the abnormal gene has a 50% chance of passing this gene on to their child, making that child a carrier. However, the parent who is not a carrier does not have a recessive gene to pass on. Remember that two copies of the recessive gene must be present to inherit the recessive abnormal trait, so if one parent is not a carrier, the trait cannot be inherited.
How Do I Know Whether I’m a Carrier?
Genetic carrier screening can be performed to determine if an individual is a carrier for a recessive genetic disorder. The screening test uses a sample of saliva or a blood draw to analyze DNA.
The individualsmost likely to be a carrier of an abnormal recessive gene is tested first. If the test results reveal that this individual is a carrier, then it will be advised that the other partner be tested.
There is no specific timeline required for the performance of the test. However, the earlier the test is performed, the more time a couple has to plan for their pregnancy, as well as for the arrival of their child.
Working With a Genetic Counselor To Understand Your Test Results
Genetic counselors are healthcare professionals that are trained to discuss family medical history in terms of reproductive planning as well as prenatal testing options and results. These individuals are also trained to counsel couples and provide emotional support through the testing process.
Working with a genetic counselor will help you understand the results of your genetic carrier screening test as well as further testing options.
