What do the results mean?

The results of genetic tests are not always straightforward, which often makes them challenging to interpret and explain. When interpreting test results, your doctor or genetic counselor considers your medical history, family history and the type of genetic test that was done.

A positive test result means that the laboratory detected a mutation (change) in a gene known to cause FTD. Depending on your health status, this result may confirm an existing diagnosis or it may indicate that you are at increased risk for developing FTD in the future. A positive test result may have implications for other blood relatives.

A negative test result means that the laboratory did not find a mutation in the tested gene. This negative test result must be interpreted with caution. Sometimes, a negative test result can suggest a sporadic form of the disease. In this case, other family members are not thought to be at increased risk for the condition. However, in other cases, a negative test result does not entirely exclude the possibility of a familial condition. It is important to discuss the test results with a genetic counselor or doctor to better understand the implications for yourself and family members.

In rare cases, the genetic test result is inconclusive. This occurs when the test identifies a natural variation in a gene, called a polymorphism. Polymorphisms are common in the population and, generally, do not affect your health. Sometimes is it difficult to know if a variation in a person's DNA is a very rare (uncommon) polymorphism or a mutation (a change in the DNA that will cause a genetic disease). If the genetic test reveals a change that has not previously been associated with a disorder in other people, this can sometimes be difficult to determine, and, therefore, results remain uncertain.