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What is Huntington's Disease?

November 26, 2021

Huntington's Disease Youth Organization

HDYO has more information about HD available for young people, parents and professionals on our site:


Huntington’s Disease (HD) is known as a ‘genetic neurodegenerative disorder’. The word genetic means that this disease is passed down from one generation to the next. Neuro relates to the brain. Degenerative means something that gradually gets worse over time. Disorder is another word for disease. So, when people describe HD, they are saying it is a disease passed down from one family member to another, which affects the brain, and gradually gets worse over time. Brain HD is caused by an expanded gene in our DNA. Everyone has the gene that causes HD, but people that develop the condition have a longer version of the gene. It is that expansion which causes the gene to work improperly and eventually, people to develop symptoms. When the person with HD has a child, the child is what we call “at-risk for HD”. This means that they have a 50% chance of inheriting the mutated gene that causes HD. There are some family planning options for having children to potentially lower or limit the risk of HD even though their parent has HD, but these options are not easy or always widely available.

Main Types of Symptoms (3 M’s)

Symptoms of HD can be divided into three main types, an easy way to remember them is to know them as the 3 M’s: Movements, Mind and Mood. Movements are probably the most visible symptom of HD, making it gradually difficult to walk, keep their balance and stay still. The mind is affected in people with HD as it is a brain condition, and some can develop cognitive (thinking) symptoms. This can include repetitiveness, memory loss, difficulty in planning and concentration, becoming fixated or obsessed or lack of insight. And finally, mood, changes, often referred to as behavioural symptoms, can be very difficult to cope with. Symptoms can make one feel anxious, depressed, lethargic or easily agitated. This can also completely change how people behave, and some may become uncharacteristically abusive (emotionally/physically).

Everyone is Different

It is important to remember that symptoms of HD can affect everyone differently, even within the same family. For example, one person with HD may have a lot of movements but only slight mood changes. Another person may experience all three types of HD symptoms.


Hands The onset of symptoms can begin at any age, including Juvenile onset HD. However, most people typically develop these between 30 and 50 years. The timing of symptoms depends on the length of the huntingtin gene and other genetic factors. Maintaining a healthy lifestyle is always recommended.

The Figures

Worldwide roughly one person in every ten thousand is affected by HD, so it is quite a rare disease. However, some places have more cases of HD than others. For example, the condition is common in places like Europe or North America, and there are also ‘clusters’ where HD is extremely common in a localized area – most of these are in South America. HD is thought to be far less common in places such as Asia and Africa, although not enough research has been done to know exactly how many people are affected.


Currently, there is no cure for HD; however, many symptoms may be treated with medications, physical or behavioural therapy and support. More and more, HD research is in a promising place to find new ways to treat symptoms and slow down and stop HD, creating great hope for the future.


One of the most important ways to cope with HD is to find support. We know that learning about HD is complicated and daunting, especially if it is impacting you. HDYO was founded to support young people in HD families worldwide. We encourage you to contact HDYO with any questions you may have. We are always here to listen and help. We also encourage you to navigate through our site to find a variety of educational and support resources for all age groups and areas of need.

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