To make a diagnosis of Huntington's disease (HD), a genetic test, using a blood sample, will be performed. This test is usually combined with a complete medical history and other neurological and laboratory tests. For individuals who are at risk of carrying the HD gene, testing can be performed before symptoms occur.
Although a diagnosis of HD is largely based on clinical symptoms, the gold standard for diagnosis is genetic testing.
The most effective and accurate method of testing for HD—called the direct genetic test—counts the number of CAG repeats in the HD gene, using DNA taken from a blood sample. The presence of 36 or more repeats supports a diagnosis of HD.
For a definitive diagnosis, a genetic test is required. This will normally involve a blood sample being taken and sent to a specialized center for examination. The test can determine how many CAG repeats are present in the HTT gene.
Using a blood sample, the genetic test analyzes DNA for the HD mutation by counting the number of CAG repeats in the huntingtin gene. Individuals who do not have HD usually have 28 or fewer repeats. Individuals with HD usually have 40 or more repeats. Deciding to be tested for Huntington's disease can be difficult.
Genetic testing for Huntington's disease has a 99.9% accuracy rate; however, keep in mind that if you fall in that mid-level range of having 27 to 35 CAG repeats, it's not known whether or not your children will eventually develop Huntington's disease.
A blood test to check for the Huntington's disease gene can confirm if you have the condition.
Huntington's disease has been around for a long time, but in 1872, George Huntington was the first to describe it entirely and observe how it affected families genetically. Despite his work, HD patients still tended to be misdiagnosed with something else. The most famous example is Woody Guthrie.
Pre-symptomatic testing for Huntington's disease, also known as predictive testing, is a bit more complicated than diagnostic testing. Pre-symptomatic testing happens when people who know they may be at risk for HD but who do NOT have symptoms seek testing to learn whether they will get HD in their lifetimes.
Symptoms of Huntington's disease usually develop between ages 30 and 50, but they can appear as early as age 2 or as late as 80. The hallmark symptom of Huntington's disease is uncontrolled movement of the arms, legs, head, face and upper body.
In order to receive a diagnosis, you will need to obtain a referral from your GP to see a Huntington's disease specialist. The initial consultation may include: Discussion of family history. Your current knowledge of Huntington's disease.
In medicine and statistics, a gold standard test is usually the diagnostic test or benchmark that is the best available under reasonable conditions. In other words, a gold standard is the most accurate test possible without restrictions.
Parkinson's disease and Huntington's disease are both model diseases. Parkinson's disease is the most common of several akinetic-rigid syndromes and Huntington's disease is only one of an ever growing number of trinucleotide repeat disorders.
Early Stage: In this stage patients can still perform most of their usual activities. They may still be working and may still be able to drive. Involuntary movements are mild and infrequent, speech is still clear, and dementia, if present at all, is mild.
Although anyone can develop HD, it tends to run in people of European descent (having family members who came from Europe). But the main factor is whether you have a parent with HD. If you do, you have a 50% chance of also having the disease.
In Australia it is estimated that over 1,800 people have Huntington's Disease and approximately 9,000 are at risk (Huntington's NSW ACT website, 2019) with a reported prevalence rate in Australia which ranges from 4.5 per 100,000 to 6.5 per 100,000 (Pringsheim et al., 2012).
Huntington's disease is a condition that damages nerve cells in the brain causing them to stop working properly. It's passed on (inherited) from a person's parents. The damage to the brain gets worse over time. It can affect movement, cognition (perception, awareness, thinking, judgement) and mental health.
Medical imaging techniques, such as computerized tomography (CT) and magnetic resonance imaging (MRI) can reveal atrophy of the caudate nuclei, which is observed in the early stages of Huntington's disease.
Genetic Tests for Huntington's Disease
The current offering of at-home tests does not provide information about the risk for Huntington's disease . People who have a family history of the disorder who want to know if they have the gene must undergo testing through a health care professional and a genetic counselor.
Although all modalities capable of structural brain imaging will demonstrate morphological changes of Huntington disease, MRI has the greatest spatial and contrast resolution and is thus preferred.
There have been reports that juvenile onset Huntington's chorea is almost always inherited from the father, and that late-onset Huntington's chorea is inherited more often from the mother than from the father.
Myth 1: HD is a male disease. Fact: Both men and women can be born with the HD gene.