Diagnosing Huntington's Disease
There are generally two types of tests used in diagnosing Huntington's disease: genetic testing and imaging tests.
The discovery of the Huntington disease gene in 1993 resulted in the creation of a direct Huntington's disease genetic test. This genetic test is used to make or confirm a diagnosis of Huntington disease in an individual showing Huntington's disease-like symptoms. Using a blood sample, the genetic test analyzes DNA for the Huntington's disease mutation (see Huntington's Disease Genetic Testing).
The physician may also ask the individual to undergo a brain-imaging test. Computed tomography (CT scan) and magnetic resonance imaging (MRI) provide excellent images of brain structures with little, if any, discomfort. These imaging tests cannot be used to diagnose Huntington's disease by themselves because other conditions can cause similar-looking changes on imaging tests. Also, a person with early symptoms of Huntington's disease can have a normal MRI or CT scan. However, when used in conjunction with a family history and record of clinical symptoms, CT scans or MRIs can be important diagnostic tools.