Your GP will refer you to a neurologist (specialist in treating disorders of the brain) if they feel your symptoms need further investigation.
The neurologist will ask questions about your symptoms, such as whether you have had any recent emotional problems, to see if it is likely that you have Huntington's disease and to rule out other similar conditions.
They may also test a number of physical functions, such as your reflexes, eye movements, balance, walking, general movements and strength. All of these can be affected by Huntington's disease.
Confirming the diagnosis
If you are showing symptoms of Huntington's disease and it is known to run in your family, or if your doctor strongly suspects that you have the disease, genetic testing can confirm the diagnosis.
It is important to realise that the diagnosis is based on a combination of the doctor recognising the pattern of changes on the neurological examination, family history and the genetic test result. It is possible to have the gene change and still be healthy.
Taking a genetic test
The children of someone with Huntington's disease can take a genetic test (after the age of 18) to see if they have inherited the disease. If they have inherited the faulty gene, they will develop Huntington's but it is not possible to work out at what age.
You can ask your GP or neurologist to arrange an appointment for you at a regional genetic clinic. You will have some counselling, then two blood samples will be taken. Your DNA is extracted from the blood sample and analysed to see if you have inherited the faulty gene.
You may have to wait two to four weeks for the test results.
Having a brain scan
In the early stages of Huntington's disease there may be no specific changes on the brain scan. A doctor may use a brain scan at any stage of the illness if there is a concern that there may be problems in addition to Huntington's disease.
A CT scan uses X-rays and a computer to create a detailed image of the brain. A CT scanner is a large ring-shaped machine. The X-ray scanner inside the ring rotates in small movements around your body as you lie on a bed that moves backwards and forwards through the ring. As you move through the machine, the scanner uses a series of X-ray beams to scan your brain.
A MRI scan uses strong magnetic fields and radio waves to produce a detailed image of the brain. The MRI scanner consists of a large tube that contains a series of powerful magnets. You lie inside the tube during the scan.
Getting tested in pregnancy
If you are pregnant and already known to have the Huntington’s disease gene, it is possible to have a direct test on the pregnancy at 11 weeks. This needs careful consideration and can be discussed with a genetic counselling team.
If one half of a couple is at risk of Huntington's disease but does not want to find out if they have the disease, and the couple would like to have children free of risk, then more complex indirect genetic testing is needed. This needs to be discussed with the genetic clinic. One option is preimplantation genetic diagnosis.
Preimplantation genetic diagnosis
Preimplantation genetic diagnosis can be used when one partner is known to have the faulty gene. This is a direct test.
It involves having in-vitro fertilisation (IVF) treatment, then genetically testing the embryo in a laboratory to see if it has the faulty gene. The embryo will only be placed inside the woman if it does not have the faulty gene.
The procedure is also an option for couples where one partner has a 50% risk and does not want to be tested. An embryo that is not at 50% risk will be placed inside the woman.
Preimplantation genetic diagnosis is not a straightforward procedure, and it raises a number of issues that need to be considered in detail. For more information, read the Human Fertilisation and Embryology Authority's guidance on the procedure (links to external site).
