June and Wills Fundraising for HD

Huntington's disease, also sometimes known as Huntington's chorea, or simply HD, is the most common genetic cause of chorea. This incurable, neurodegenerative disorder (neurodegenerative means that HD affects the brain and central nervous system causing worsening function over time)was named after the American physician George Huntington who accurately described it in 1872. Prevalence, per country, is up to 10 people in 100,000 in countries with a predominantly Caucasian population, but is less prevalent in countries with predominantly Asian populations.

Onset of symptoms can begin at any age, although the mean age of onset is 35 to 44 years of age. The first symptoms of the disease may be physical e.g. small involuntary movements or problems with coordination or they may be cognitive or psychiatric. Less commonly, onset is before the age of twenty, and the condition is classified as juvenile HD (also known as akinetic-rigid HD or Westphal variant HD )- which progresses faster with slightly different symptoms. In 1993 genetic testing was made possible with the discovery of a single causal gene, the first non-sexlinked dominant disease gene to be found, as such counselling for HD had to be developed and became a model for other dominant disorders. The test can be performed before the onset of symptoms, at any age when it is called predictive testing or to confirm a diagnosis of HD in which case it is called diagnostic testing.

The disease runs in families: it is inherited dominantly so children of an affected person are 50% at risk of inheriting the genetic change that causes HD. The exact way HD affects an individual varies, even between family members, but there is a characteristic progression. The earliest symptoms are a general lack of coordination and an unsteady gait. As the disease advances uncoordinated, jerky body movements become more apparent, as does a decline in mental abilities and behavioral and psychiatric problems. Physical abilities are gradually lost until full-time care at home or in a nursing home setting becomes necessary and the decline in mental abilities generally results in the person losing the capacity to make decisions for themselves. Although HD itself is not fatal, complications reduce life expectancy to around twenty five years after the onset of symptoms.
The mechanism of the disease is not fully understood, but a number of factors have been identified. The genetic change results in the production of a cell protein whose molecular shape and size is altered. The precise effect this has on brain cells is not understood, but either the direct presence of this altered protein or it?s interaction with other cell components gradually leads brain cells to function less effectively and then to die. Although there is no cure for HD there is an enormous amount that can be done to promote quality of life and manage the symptoms of the disease and other sections of the information and resources part of our web site explains this in more detail.

The greatest cause for optimism is the current research into HD. Organizations like the Hereditary Disease Foundation in America and the European Huntington?s Disease network (Euro-HD) are leading the way in the development of a cure or treatment for Huntington?s disease. Huntington?s disease is now the sixth most researched condition in the world. Much of this work is supported by charities like the Scottish Huntington?s Association which along with other organizations like the Woodie Guthrie Foundation also strive to increase public and professional awareness about the disease.

Current research directions include determining the exact effect of the altered protein produced by the genetic change, on brain cells, improvement of animal models to speed research, clinical trials of pharmaceuticals to treat symptoms or slow the progression of the disease, and employing procedures such as stem cell therapy with a view to repairing damage caused by the disease. Research is also currently looking into ways in which the gene might be ?switched off? to prevent it from making the faulty protein.
Symptoms can appear at any age with the mean onset age between 35 and 44 years. After the disease process begins but before diagnosis there may be a stage of subtle changes in personality, cognition, or physical skills. Physical symptoms are usually the first to cause problems and to be noticed, but at this point they are commonly accompanied by unrecognized cognitive and psychiatric ones. Almost everyone with Huntington's disease eventually exhibits physical symptoms, but the onset, progression and extent of cognitive and psychiatric symptoms vary significantly between individuals.

The most characteristic initial physical symptoms are jerky, random, and uncontrollable movements called chorea. Muscle rigidity (sometimes called dystonia) becomes more pronounced as HD progresses. Rigidity and dystonia become evident as the disorder progresses, these gradually become the dominant physical symptomsAbnormal movements are initially exhibited as distinct chorea, incoordination, motor impersistence, and slowed saccadic eye movements, but as the disease progresses, any function that requires muscle control is affected, resulting in physical instability, abnormal facial expression, and difficulties chewing, swallowing and speaking. Swallowing difficulties and involuntary movements commonly lead to weight loss and this is exacerbated by an underlying increase in metabolic activity which is poorly understood and may lead to malnutrition. Sleep disturbances are also associated symptoms. Juvenile HD differs from these symptoms, in that it generally progresses faster, exhibits chorea briefly, if at all, and commonly includes seizures reported prevalence of behavioral and psychiatric symptoms in HD.