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Genetic risk

At Risk of Huntington’s Disease

Some families may already be familiar with Huntington's disease because they have relatives with the illness. Others may have never heard of Huntington's and may be shocked by a diagnosis in the family. Huntington's disease is caused by an expansion in a single gene that's passed down from a parent. Huntington's follows an autosomal dominant inheritance pattern. This means that a person needs only one copy of the nontypical gene to develop the disease. Every child conceived naturally to a person who has Huntington’s disease has a 50% chance of inheriting or not inheriting the expanded gene which causes the illness. If you have not inherited the expanded gene, you will not develop the disease and cannot pass it on to your children.

This short video animation Understanding Autosomal Dominant Conditions  from the National Centre for Medical Genetics explains autosomal dominant conditions. It was produced in 2014 by University College Dublin with support from the Health Research Board and Shire Pharmaceuticals. 

While it is obvious that people with Huntington's face difficulties in living with their illness, people who are at-risk may also experience significant challenges. It can make a big difference if you know what help is out there and get the support and information you need. It can also be helpful to meet others in the same situation for peer support. Learning more about research or engaging in observational 

Genetic Testing

A genetic (predictive) test is available to determine whether a person has or has not the gene that causes Huntington's disease. You usually need to be over eighteen years of age. Taking the test is a personal decision and varies from person to person. Genetic counselling is available prior to testing and provides an opportunity to consider and understand the possible outcomes, the resources you may need, and whether the decision to take the test is the right one for you at that time. Details on genetic counselling and testing are available from; The Department of Clinical Genetics, Our Lady’s Children’s Hospital, Crumlin, Dublin 12. Tel: (01) 409 6739, Website: www.olchc.ie

Following a gene test result, it is common to experience emotional ups and downs. People with a negative result may experience ‘survivor guilt’, particularly if other members of their family have received a gene positive result. Huntington's disease is often referred to as a family disease and it is important to recognise that each family member, whether they have the disease or not, will be impacted by Huntington's.

Family Planning

A genetics clinic can provide information on family planning options. Pre-implantation genetic diagnosis (PGD) can help couples with a known risk of a genetic condition avoid passing it on to their children. It involves undergoing in-vitro fertilization (IVF) treatment to allow embryos to be tested before they are implanted in the womb. PGD is an expensive and time-consuming way to become pregnant and carries risks associated with IVF.

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Gene Positive family members

Receiving a gene positive predictive test result may be overwhelming immediately afterwards. It is often very difficult to recall what was discussed. The results may become more real in the days and weeks that follow. It is important to realise that emotional turmoil is quite normal and will usually ease considerably as day to day life takes over once again. However, if you experience continuous anxiety or are unable to sleep you should speak to your genetic counsellor or GP. Huntington's Disease Association of Ireland can also provide support.

Huntington's disease is typically a slow progressing illness. As a result, you could have considerable time to carry on as per usual after a genetic test diagnosis. The timing of symptom onset is dependent on many things including the function of other genes, your general health and environmental factors such as diet and exercise.  As yet, there is no effective treatment to delay or slow down Huntington's disease, but there are ways you can help yourself and learn to manage your illness.

Research suggests that leading a healthy lifestyle may help to delay the onset and can help in the management of symptoms. The more informed you are, the better you will be able to understand what the disease is all about and plan ahead. Learning and understanding how the disease progresses will help you adjust to any changes you may experience. There is a vibrant international Huntington's community working together to find effective treatments and improve standards of care. More is known about Huntington's disease today than at any time in the past.

Research

Significant progress has been made by researchers world-wide to understand Huntington's disease and to develop potential therapies to halt or reverse the disease. There is now greater hope than ever before that therapies will be found to fight Huntington’s disease. HDBuzz is an excellent research news resource. Enroll-HD gives family members impacted by the illness an opportunity to help advance Huntington's disease research.

Delaying onset

Studies suggest that by maintaining good nutrition and leading a mentally and physically healthy and active lifestyle, you can delay the onset of symptoms. Keeping physically and intellectually active, maintaining a healthy diet, enjoying life and avoiding excessive stress will have a positive impact for people at risk. Tips include:

  • A healthy diet – fresh, nutritious, well-balanced meals with lots of fruit vegetables and whole grains. Dietary factors considered good for brain health include vitamin B-12,  anti-oxidants and anti-inflammatory agents. How to eat well - HSE.ie
  • Regular exercise – aim for 30 minutes 3 times per week  - can include walking, gardening, dancing, yoga, Tai Chi etc.
  • Mental Stimulation – new learning, puzzles and crosswords, reading aloud etc.
  • Adequate Sleep - remove distractions from the bedroom, use relaxation techniques
  • Emotional Wellbeing - avoid undue stress. Speak to your GP or a counsellor if you experience anxiety or depression
  • Avoid Brain Toxins – alcohol, smoking, overly processed foods etc.
  • Dental Care - proper dental care is necessary for everyone  to keep teeth and gums healthy . Maintaining a daily routine to prevent tooth decay and gum disease is particularly important for people at risk of HD. The health of teeth and gums affects communication, eating, swallowing as well as social interactions and self-esteem.

Online resources

Engagement in genetic testing will remove the uncertainty about whether a person will develop Huntington's Disease

Prof Kieran Murphy

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