Huntington’s disease (HD) is a genetic neurodegenerative disease. This means that it is a disease of the brain that is passed down from parent to child. There is currently no cure for HD, but there are some treatments that can help to ease certain symptoms. From the onset of symptoms, people with HD have a life expectancy of 10 to 25 years.
HD is not evident at birth. In fact, symptoms will usually not appear until a person is between 35 and 55 years of age, and occasionally even later in life. In rare cases, symptoms can begin at a much younger age: in children, teenagers and young adults. This early onset of the disease is referred to as Juvenile Huntington’s disease.
There are three groups of symptoms: physical, cognitive, and those affecting personality and emotions. There is no confirmed order for the onset of symptoms, and each person experiences the disease’s progression differently. For details on symptoms, please visit the Symptoms page.
What causes Huntington’s Disease?
HD is caused by a defective gene on chromosome 4 that causes an excessive build-up of the Huntingtin protein. This protein build-up damages nerve cells in parts of the brain, affecting neurological function and causing Huntington’s disease.
Genes come in pairs – one from each biological parent – and they form the basis of everything from height to eye colour to genetic health. If one parent carries the Huntington’s gene, each biological child risks inheriting the faulty gene as well. The affected chromosome is not gender-specific, so both genders have equal risk of inheriting the faulty gene. This faulty HD gene is dominant; if you inherit it, you will certainly develop Huntington’s disease at some point in your life.
Huntington’s disease is not communicable. This means it cannot be caught, as it is not an infection, and it can only be passed on at the point of conception. If you are not born with the faulty gene, you will never develop HD. HD cannot skip a generation either. The only way to inherit the disease is for it to pass directly from biological parent to child. If the parent is gene negative, their children are not at risk for Huntington’s disease.
HD is acquired genetically. This means that you are only at risk of developing the disease if one or both of your parents also has the disease. The faulty gene can only be passed on at point of conception. You cannot “catch” Huntington’s disease (it is not communicable), and it cannot skip a generation.
Every person with an HD-positive parent has a 1-in-2 chance of inheriting the faulty gene that causes HD. If your parent is at risk of or has the disease, then you and your children are also considered at risk of inheriting the faulty gene which causes the disease.
Some people diagnosed with HD may not be aware that they have a family history of the disease. Historically, HD was misdiagnosed as a number of other conditions, so many families were unaware of their genetic risk. In other cases, the person carrying the faulty gene may have passed away from other causes (of an unrelated condition or in an accident) before symptoms appeared, so the family is unaware of the possibility of the genetic disease.
The decision to have children can be difficult if you or your partner are at risk for HD. Some people conceive naturally, some adopt, some seek IVF treatment and some choose not to have children. You may receive unsolicited advice from people about your decision, but it is important to remember that it is solely you and your partner’s decision; you should never feel pressured towards a particular decision. Speak with your doctor for more information if you are finding the process difficult, and if you decide you would like information on IVF, you can also speak with the Genetic Health Clinic:
Genetic Health Queensland
Royal Brisbane Women’s Hospital
Herston Road, Herston, QLD 4029
Telephone: (07) 3646 1686
Fax: (07)3636 1987