To diagnose Huntington disease, a doctor may perform a neurological exam and ask about the person's family history and symptoms. Imaging tests may be performed to look for signs of the disease, and genetic testing can be done to determine if the person has the abnormal gene.
Molecular genetics testing
Molecular genetics testing is used to determine if a person has an allele, or gene variant, that predisposes to Huntington disease. It can be used to confirm a clinical diagnosis of HD and for predictive testing in asymptomatic individuals. The most common approach used is direct mutation analysis, which involves analysis of the person's DNA to estimate the length of the CAG repeat mutation.
Routine screening of the general population is not recommended, especially due to the lack of effective intervention to stop the onset of disease. However, it should be considered in individuals at an increased risk, that is, in those with a family history of HD. This is done using molecular genetics testing as described above. Predictive testing, in affected families, is also used to determine the disease status in females of child-bearing age and pregnant women to assess the risk of transmission to their children. Similarly, prenatal testing can also be done to determine if a fetus is affected.
Those who are considering genetic testing may want to consult with a genetic counselor, who can help them to better understand the pros and cons of this type of testing.
These imaging tests can provide an image of the brain showing areas of degeneration. They are not very useful, however, in early-stage HD because they are unable to show small regions of brain deterioration.
- CT scan
- PET scan
For more on imaging studies, see the web site Radiologyinfo.org.