Huntington’s Disease Patient Fact Sheet

What is Huntington’s disease?
Huntington’s disease, which is often called HD, is a hereditary disorder of the central nervous system. It used to be known as Huntington’s Chorea or HC. Huntington’s disease usually develops in adulthood and can cause a very wide range of symptoms—including physical, mental and emotional symptoms.

What causes Huntington’s disease?
Huntington’s disease is caused by a faulty gene on chromosome 4. The gene, which produces a protein called huntingtin, was discovered in 1993. Though the mechanism is not yet understood, the faulty gene leads to damage of the nerve cells in areas of the brain including the basal ganglia and cerebral cortex. This leads to gradual physical, mental and emotional changes. A person with a parent who has Huntington’s disease is born with a 50–50 chance of inheriting the faulty gene. Anyone who inherits the faulty gene will, at some point in their life, develop the disease. A genetic test is available from Regional Genetic Clinics throughout the country. This will usually be able to show whether someone has inherited the faulty gene, but it will not show the age at which they will develop the disease.

What are the early symptoms of Huntington’s disease?
The symptoms of Huntington’s disease usually develop when people are between 30 and 50 years old, although they can start much earlier or much later and can differ from person to person, even within the same family. Sometimes, the symptoms are present for a long time before a diagnosis of Huntington’s disease is made. This is especially true when people are not aware that Huntington’s disease runs in their family.

The early symptoms include slight, uncontrollable muscular movements; stumbling and clumsiness; lack of concentration and short-term memory lapses; depression and changes of mood, sometimes including aggressive or antisocial behavior. Great strain is put on relationships if unexpected temper outbursts are directed toward a person’s partner or family. The time before a diagnosis is made can be very confusing and frightening because people do not understand what is happening and why. Some people who know they are at risk anticipate the first signs that they are developing the disease. They may worry about simple things such as dropping a cup, forgetting a name or becoming unusually bad-tempered. Most people do these things occasionally—whether they are at risk from Huntington’s disease or not—so they could be worrying unnecessarily. Anyone who is concerned should speak to their doctor who may refer them to a neurologist for tests. These tests could include a number of simple assessments and possibly a brain scan. The genetic test referred to earlier may also be used to aid diagnosis.