While all aspects of the medical field are constantly evolving, this is particularly true of genetic testing. Currently genetic tests are available and recommended for a limited number of medical conditions, though more tests become available each year.
Genetic testing is not recommended to try to assess risk for coronary artery disease, the acquired adult form of heart disease that leads to heart attack. However, if you are an adult who was born with a heart defect (congenital heart disease) and you are interested in having children, genetic testing can help assess the risk of your child inheriting that condition. Genetic tests are not available for all forms of congenital heart disease. Your cardiologist can help you determine if you are a good candidate.
Another developing areas in genetic testing is that of identifying patients who may not respond well to certain medications, such as antiplatelet drugs. These patients are called poor metabolizers for that medication - that is, their bodies do not process the medication as would be expected due to genetic variations in the enzyme responsible for processing the medication. Poor metabolizers for certain drugs can be identified through a genetic test. The commonly prescribed antiplatelet medication clopidogrel (Plavix) is one example of a medication for which genetic testing can identify poor metabolizers. The value of genetic testing in a routine fashion to identify poor metabolizers is still unknown.
How Does It Work?
A blood sample is sent to a lab where a scientist analyzes the DNA in the blood, which contains genetic information. The scientist looks for information patterns in and around the genes called “markers.” If someone has a particular marker that is known to be associated with a disease, that person should carry a specific gene. Presence of a gene that is associated with a disease only indicates that the person being tested may be predisposed to have that disease. It does not necessarily mean that the person will develop the disease.
If you choose to pursue genetic testing, it is important to do so through a validated laboratory in the context of trained genetic counseling and experienced cardiovascular physicians, who can explain the results and place them in the context of your future cardiovascular care.
How Is It Performed?
Before you have blood drawn and sent to a lab for analysis, you will meet with a counselor or other medical professional who specializes in genetic testing. During this meeting, you will review your personal and family health histories. This meeting will help determine if, based on the condition you are seeking information about, you are a good candidate for a genetic test. You will also be advised of any limitations of the test.
The actual genetic test is like any other blood test. Having blood drawn typically only takes a few minutes. You will be asked to roll up your shirt sleeve (if necessary) and the medical professional who will be drawing the blood will swab the area where the needle will be inserted with an alcohol wipe. A rubber tube may be tied around the upper part of your arm, or you may be asked to make a fist, to make the veins stand out more and easier to access.
A needle attached to a small test tube will be inserted into your vein and blood will begin to flow into the tube. When a sample that is appropriate for the test has been gathered, the needle will be removed, and you may be asked to press on a piece of gauze placed over the insertion site. This pressure will help stop any bleeding from the tiny puncture site. A bandage will then be placed over the site where the needle was inserted.
Your blood sample will then be sent to lab technicians for analysis. You will receive information when you have the blood test as to when you can expect results.
Is It Safe?
Having blood drawn by a qualified medical professional is very safe. You will experience momentary pain when the needle is inserted, and you may experience bruising at the needle insertion site after the test is complete. If you have an allergy to latex or to any adhesives, let the person know who is drawing the blood, so he or she can make any necessary adjustments.
Questions to Ask Your Doctor About Genetic Tests
The following questions can help you talk to your physician about a genetic test. Print out or write down these questions and take them with you to your appointment. Taking notes can help you remember your physician’s response when you get home.
- What will a genetic test tell us about congenital heart disease, drug metabolism, or some other condition?
- How accurate is the test?
- Are there any ethical considerations related to the test?
- Can you refer me to a genetic counselor?
Please print this list of questions here. Take them with you to the doctor and share them with friends and loved ones when you are encouraging them to see their doctors.