Huntington's disease explained

What Huntington's disease is

Huntington's disease is caused by a fault in a single gene called the huntingtin gene. This fault leads to the gradual loss of certain nerve cells deep in the brain that help control movement, thinking and mood. As these cells are damaged over the years, the condition slowly progresses. It is a genetic condition, meaning the fault is present from birth, but symptoms usually do not appear until a person is between about 30 and 50 years old, although they can start earlier or later. Because the brain areas affected control several functions, Huntington's disease causes a mix of movement problems, changes in thinking and changes in mood and behaviour. The combination and severity vary from person to person and change over time.

How it is inherited

Huntington's disease follows a pattern called autosomal dominant inheritance. This means that if a parent carries the faulty gene, each of their children has a one in two, or fifty per cent, chance of inheriting it. Almost everyone who inherits the faulty gene will develop the condition during their lifetime if they live long enough. Because the disease often appears after people have had children, families may be affected across generations. This inheritance pattern is why genetic counselling is so important: it helps people understand their own risk, the implications for their children, and the options available, including predictive testing before symptoms appear. Occasionally the condition arises in a family for the first time. Understanding the genetics helps families make informed, personal choices.

Symptoms and how they progress

Huntington's disease affects three main areas, and early signs are often subtle. Movement changes can include small involuntary movements called chorea, which look like fidgeting or jerking, as well as stiffness, clumsiness and problems with balance and, later, swallowing and speech. Thinking changes may include difficulty concentrating, planning and remembering, and slower thought. Emotional and behavioural changes are common and can include depression, irritability, anxiety, and sometimes obsessive thoughts or personality change; these can appear before the movement problems and are sometimes the most challenging. Over many years the condition progresses so that people need more help with daily activities. The pace varies, and good symptom management and support can make a substantial difference to comfort and quality of life throughout.

Diagnosis and genetic testing

Where symptoms suggest Huntington's disease, a neurologist assesses the pattern of movement, thinking and mood changes and the family history. A blood test can identify the faulty gene and confirm the diagnosis. For people who have no symptoms but have a family history, predictive genetic testing can show whether they carry the gene, but this is a very personal decision with major emotional and practical implications. For this reason, testing is always offered alongside genetic counselling, which gives people time to consider what a result would mean for them and their family, and there is no pressure to be tested. Options such as testing during pregnancy, or a technique that allows selection of embryos without the gene during fertility treatment, may be discussed for people planning a family.

Treatment, care and support

There is no cure yet, but a range of treatments and support help people live with Huntington's disease. Medicines can ease specific symptoms such as troublesome involuntary movements, low mood, anxiety and irritability. Just as important is a coordinated team including neurologists, specialist nurses, physiotherapists, occupational and speech therapists, dietitians and psychologists, who help with movement, communication, swallowing, nutrition, daily living and emotional wellbeing. As the condition advances, more support at home or in specialist care may be needed, and palliative care focuses on comfort and quality of life. Families benefit greatly from support too, both practically and emotionally. In the UK, the Huntington's Disease Association provides information, advice and local support, and research into treatments that could slow the disease is ongoing.