What is genetic testing?
Genetic testing identifies changes in DNA, RNA, genes, chromosomes or proteins – the blueprint which instructs how we grow and develop. The result of a genetic test can often confirm or exclude a suspected genetic condition or help determine a person's chance of developing or transmitting a genetic disorder. Unlike routine blood tests, the results from a genetic test will not change over time and only need to be performed once in a person's life.
Approximately 20-50% of all individuals with frontotemporal dementia (FTD) have a known family history. This means that 50-80% of those affected have no known family history of the disorder. Sometimes, this is due to a misdiagnosis in the family with another condition, such as Parkinson disease, Alzheimer's or psychiatric illness. For this reason, individuals in the family may be at-risk for a "familial" disorder without prior knowledge. Genetic counseling and testing can help clarify this risk.
Genetic testing can be performed to confirm a suspected diagnosis of FTD, assess risk for extended family members or identify an individual with increased risk for developing the disease (predictive testing). Testing should first be performed on an affected individual to determine whether or not there is an identifiable genetic or sporadic form of the disease in the family. Genetic testing identifies a mutation in a gene known to cause FTD approximately 10% of the time.
It is important to remember that genetic testing is voluntary. Because testing has both benefits and limitations, this decision is personal and complex. The physical risks associated with most genetic tests are small and involve a simple blood draw. Most of the risks associated with genetic testing involve possible emotional, social or financial consequences of the test results. You may feel sad, angry, frightened, depressed, anxious or guilty after learning your results. Learning that one carries a mutation in a gene that results in a progressive, lethal disorder can be devastating and should be considered very carefully.
On the other hand, test results can give you a sense of relief from uncertainty and help you make informed decisions about managing your health care. The test results might impact life decisions, such as career choice, family planning, or insurance coverage. Your genetic counselor can explain in detail the benefits, risks and limitations of a particular test. It is important that you understand and weigh these factors before making a decision.
If you decide to proceed with genetic testing, often a sample can often be collected following your consultation. The sample is then sent to a laboratory where technicians look for the specific changes in one of the four genes associated with FTD. The laboratory will report the results to your doctor and/or genetic counselor who will discuss the results with you in person.