1. Find an Appropriate Testing Center
The Huntington's Disease Society of America has a list of centers that follow their guidelines for genetic testing. Other countries have similar organizations that can help as well. The testing itself can be quite complicated, involving counseling, psychological interviews, neural exams and follow-up sessions. Because there is no way to predict the onset of Huntington's disease, some people who are at risk would prefer not to know. A proper testing center will make you aware of all of your options before proceeding.
2. Take a Presymptomatic Test
A presymptomatic test is used to predict Huntington's disease before it becomes manifest. It usually entails a simple blood sample, and the results take several weeks. In the meantime, you will likely receive a physical examination and a psychological interview. A doctor may provide a neurological scan to check your brain, and counseling will be offered to prepare you for the results and discuss possible options. Each aspect of the test--psychological evaluation, physical exam, neurological exam and counseling--constitutes an entire session, so you should be prepared for multiple trips. Presymptomatic testing can't determine exactly when the onset of the disease will begin, only that the pertinent gene is present in your DNA. Research is ongoing, however, and may eventually be able to provide a more accurate method of prediction.
3. Get a Confirmatory Test
A confirmatory test is given after the symptoms have appeared in order to determine if Huntington's disease is the cause. It follows the same procedure as a presymptomatic test, checking the blood for the presence of the gene and conducting an array of examinations to determine its immediate effect on you. Counseling becomes even more important in a confirmatory test than it would in a presymptomatic test. If the condition is manifest, you need to be prepared for the changes it will make in your life sooner rather than later.
4. Consider Testing for Juvenile Onset Huntington's Disease
At-risk patients under the age of 18 shouldn't be tested for Huntington's disease. They usually lack the maturity to handle the possible ramifications and can be subjected to undue pressure from elders. However, some cases of Huntington's disease manifest during adolescence. The symptoms differ significantly from adult cases, most notably in a stiffness or rigidity in the body rather than uncontrollable movements. It also tends to progress faster than adult cases. If juvenile onset HD is suspected, you should schedule a test to confirm it as soon as possible.
5. Discuss Prenatal Testing
Prenatal testing can be a particularly difficult decision, made to evaluate the possibility of the Huntington's disease gene in an unborn fetus. Ideally, a pre-genetic diagnostic test can check eggs shortly after fertilization and only implant those that do not carry the gene in the mother's womb. Amniocentesis can also be used to identify the Huntington gene in the fetus before it comes to term.
