There are three potential test results: positive, negative, and inconclusive. Only the positive results are meaningful, and the results can take a few weeks or months to be available.

Genetic factors likely play some role in high blood pressure, heart disease, and other related conditions. However, it is also likely that people with a family history of heart disease share common environments and other factors that may increase their risk.

The risk for heart disease can increase even more when heredity combines with unhealthy lifestyle choices, such as smoking cigarettes and eating an unhealthy diet.

Genetic testing usually examines a panel of multiple genes known to cause the specific inherited condition of interest, and other conditions that have a similar appearance. The DNA sequence in the patient’s DNA is compared to the normal reference sequence. A single change in one gene is sufficient to cause disease. In some cases, two or more mutations may be responsible for causing disease in the family.

If possible, genetic testing should be performed in conjunction with a healthcare team that has the experience and resources to study the family and to provide important counseling before and after testing. This counseling helps individuals make an informed decision about whether pursuing genetic testing is right for them. It also helps to ensure that the individual and their family are appropriately cared for and understand what the results mean.

  • positive result means the laboratory is reasonably confident it identified a gene mutation that can cause the family’s heart disease. A positive result allows at-risk family members to do predictive genetic testing. Family members who carry the same gene mutation are at risk to develop the heart condition and should be followed by a cardiologist. These individuals are also at risk to pass the mutation on to their children and these children should be examined. Relatives who do not have the family’s disease-causing gene mutation are very unlikely to develop the family’s heart condition and cannot pass the family’s mutation on to their children. However, because our understanding of the genetics of heart disease is not perfect, it is important to carefully examine these individuals if they develop any symptoms or other changes.
  • negative result means that the laboratory was unable to find a mutation capable of causing disease in any of the genes they evaluated. This result is considered unhelpful because it is still possible that there is genetic cause for a person’s heart disease that was simply not detected by the technology used or is present in a gene that was not evaluated. In this case it is not possible to offer predictive genetic testing to at-risk family members to determine their risk of developing heart disease. Therefore, all first-degree family members should continue to undergo the screening recommended for the family’s heart condition. Genetic testing may be reconsidered in the future if there is new information available about the potential genetic causes of the condition.
  • Lastly, it is also possible that the lab will find a change in a gene but be uncertain about whether the change is capable of causing a heart condition, whether the change can modify disease severity, or whether the DNA change they found simply reflects harmless DNA variation that occurs in the general population. This type of inconclusive result is often referred to as a variant of unknown significance, or VUS. A VUS does not provide any additional information for the family. Testing other affected family members may help to better understand the significance of a VUS. If it is present in all other affected family members, as would be expected if it is responsible for causing the family’s heart condition, that finding provides additional support that the VUS causes disease. This is particularly the case if there are many (more than 5) affected relatives. On the other hand, if the VUS is absent from even a single affected relative, that suggests it is not the cause of the family’s heart disease. Testing unaffected family members to see if they have the VUS is generally not recommended because it is unlikely to provide helpful information about whether the VUS can cause heart disease. As with a negative result, there is still the possibility of an inherited heart condition in the family and the recommended screening of at-risk family members should be followed.

Over time, new information may become available about whether a particular gene change can cause heart disease. In some cases this information may cause the laboratory to revise the results previously reported for that gene change. For example, a DNA change previously thought to cause disease may ultimately turn out to be harmless if it is found in enough healthy people. On the other hand, a DNA change that was previously of unknown significance could later be determined to be disease-causing if it is found to track with, or segregate, with enough patients with heart disease. Therefore, it is important to remain in contact with the health care provider who ordered your genetic testing in the event that new information comes to light that changes the recommendations made to you and your family.

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Dr. Drew Sutton