What is genetic testing?

Genetic testing identifies changes in DNA, RNA, genes, chromosomes or proteins. The results of a genetic test can confirm or rule out a suspected genetic condition or help determine a person's chance of developing or passing on a genetic disorder.

In genetic prion disease, diagnostic testing can identify the presence of the mutations in the prion protein gene that confirm the diagnosis of the genetic form of prion disease. A negative genetic test can rule out the possibility that a patient has a genetic form of prion disease. Predictive genetic testing can identify an increased risk of developing prion disease, even if you are not yet showing symptoms. Genetic testing can be performed with a simple blood sample. A family history of prion disease is usually present in only 40% of cases of genetic prion disease. This means that in 60% of genetic cases of prion disease there is not a known family history! In these cases, however, a careful review of all biologically related family members often reveals a history of "Alzheimer's," "Parkinson's", or psychiatric illness that was likely misdiagnosed. Therefore, it is generally necessary to do genetic testing if you want to exclude the possibility of genetic disease. Because some families may have a genetic mutation in their family, but not know it, they may not know that they have a "familial" disease.

Genetic testing is voluntary. Because testing has both benefits and limitations, the decision about whether to be tested is a personal and complex one. The physical risks associated with most genetic tests are very small. Many of the risks associated with genetic testing involve the emotional, social or financial consequences of the test results. You may feel angry, depressed, anxious, or guilty about your results. Learning that one carries a gene for a fatal disease 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 help you make 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 be collected during your consultation. The sample is then sent to a laboratory where technicians look for the specific changes in the prion gene. The laboratory will report the results to your doctor or genetic counselor.

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