1. Look for a History of Huntington's Disease in Your Family
Huntington's disease is a genetic condition that passes down through a family line. It's caused by a mutation in a specific gene, known as the Huntington's disease gene, which appears on chromosome number four of your DNA. If one of your parents has Huntington's disease, then there is a 50 percent chance that you will eventually develop it as well. Though a small percentage of Huntington's disease carriers develop it without previous genetic evidence, the first step in identifying it is to see if there is a history of the disease on either side of your family.
2. Check for Symptoms
Symptoms of Huntington's disease usually appear in middle age, though juvenile-onset Huntington's disease can take place in childhood or adolescence. For adult HD, the symptoms begin with a slight loss of coordination, growing depression, recurring irritability, involuntary movements and increased difficulty in formulating complex thoughts. You may also note a loss of weight as the condition speeds up your metabolism. Symptoms worsen as the condition progresses, but in early stages they can easily be mistaken for something else. Proper testing can help to eliminate other possibilities.
With juvenile-onset Huntington's disease, the symptoms are a little different. Clumsiness and lack of coordination is there, but it usually stems from a stiffness in the limbs rather than jerky, uncoordinated movements. Cognition may begin to suffer, as the child struggles to process information and learning slows down. Changes in emotional behavior are common, and the child may suffer from seizures as well. Many cases of juvenile-onset Huntington's disease spring from the father's side of the family, so check the child's genetic history there in addition to conducting other tests.
3. Undergo a Presymptomatic Test
A presymptomatic test is made before any symptoms appear in order to confirm the presence of the Huntington's disease gene. This is a lengthy and complex process. The test itself is made with a blood sample and may take several weeks. It basically counts the number of "repeats" in the Huntington's disease gene; someone with the condition will have considerably more CAG "repeats" than someone without. In addition to the test itself, you will likely undergo a neurological exam, a physical exam, a psychological evaluation and a series of counseling sessions to prepare for the possibility that the condition is manifest. Though the test can confirm the presence of Huntington's disease, it is impossible to predict exactly when symptoms will start to appear.
4. Schedule a Confirmatory Test
A confirmatory text is essentially no different than a presymptomatic test. It follows the same procedure and involves the same mixture of physical and psychological evaluation. It's usually conducted after the symptoms have appeared in order to eliminate any other possibilities as causes. Both presymptomatic and confirmatory tests should be undertaken by centers which follow the proper guidelines. The Huntington's Disease Society of America (HDSA) has a list of approved centers in the United States, and similar organizations exist in other countries.
5. Use Prenatal Testing
You can test for the presence of Huntington's disease in an unborn child at risk of the condition by performing a number of different examinations. Amniocentesis examines the amniotic fluid for genetic abnormalities. Pre-genetic diagnostic testing examines fertilized eggs for the Huntington's disease gene and reinserts those that are "safe" into the mother. Counseling is available for at-risk parents hoping to have children, and includes discussion of not only testing options but alternate possibilities such as surrogate parenting and adoption.
