• Even though you are positive for the gene, does that mean you are for sure going to develop symptoms?

If you have the gene for HD then one day you will get symptoms. The problem is that no doctor can currently tell you when you will get symptoms or what they might be (e.g. chorea vs depression/anxiety vs memory problems).


Typically people with the gene get symptoms between 35 & 55 years old, but HD can come on earlier or later. I have just diagnosed a man with HD at 94. He was well until 92.


It’s important to realize that having the gene is not the same as having HD. To have HD you have to have symptoms whereas people who have the gene & who are well are normal until they get symptoms of HD.


If a person does not have the gene then they cannot get HD.



  • My Grandad has HD and started showing symptoms around 71 years old. He is now 81 and in the later stages of it. My Mum was tested and has HD, she is now 53 and shows no symptoms. She has exactly the same amount of repeats as my Grandad (I’m unsure of the exact number). These are my questions:
    • As my Grandad didn’t develop symptoms until later life and my Mum still has no symptoms if I have the gene does this improve my chances of getting symptoms in later life with the same count? And if so how likely is this?
    • If I do have a higher count than them does this mean I will get symptoms earlier than my Mum and Grandad?
    • How likely is it I’ll have a higher count?

This is an very interesting questions about the age of onset of symptoms and the limits of information that a predictive test can provide. We do know that there is a relationship between the CAG repeat size and age of onset, but it does not account for all the variability. Scientists are still looking in to the question of what other factors may determine age at onset. Currently we’re not able to give someone an accurate idea of the age when symptoms will develop. How symptoms present can also vary within families.


Although the number of CAG repeats can sometimes increase when passed on, this is more likely to happen when the HD gene fault has been passed on from a father.


Unfortunately, a predictive test would not necessarily answer all your questions. It’s very useful that you are asking these types of questions so as not to have unrealistic expectations of the information a predictive test will provide. Your questions could be discussed more fully with a genetic counselor. A genetic counselor would be able to request a copy of the genetic test results of both your grandfather and mother, provided they have consented to this. It would be important to clarify for example whether your mum and your grandfather had a result in the reduced penetrance range (36-39 repeats) or the full expansion (>39 repeats).


Having a genetic counseling appointment does not commit you to any course of any action, and we often get asked questions at the stage when someone might be just thinking of having a test or simply wanting more information.



  • If I were to have HD, what can I do RIGHT NOW in my life to help slow down the effects of this disease? Should I perhaps start going to the gym on a regular basis to get a high amount of exercise?

There is now extensive evidence that exercise MIGHT delay the onset off symptoms if you are gene positive. Mice which have the human HD gene develop the disease later when they have the option to have a physically and mentally active life than if their life is un-stimulating and their opportunities for exercise are limited.


There has been one study in humans. This found that if a gene positive person was physically active then the age of onset of HD was delayed by up to 5 years. This study was very hopeful and especially so given that its findings paralleled the results of the experiments with the mice. However, it will require several more human studies to be certain if this study was correct. Also, the human study doesn’t tell us how much exercise or what type of exercise is best. What I recommend is that people at risk of HD exercise 3 to 4 times per week for about 20-30 minutes at a level sufficient to puff them out. That is, I don’t recommend incredible amounts of exercise or pushing yourself to the limits. If you do star an exercise program then you should start gently and build up your level of exercise as your fitness increases.


There are lots of other advantages from regular exercise. It’s very good for your health in general (i.e. protects you from diabetes, high blood pressure, etc) and is a very good way of relaxing and taking your mind off your worries. It’s also a good way to socialize. Many young people also feel empowered knowing that they are doing something that might make a difference and that they can exert some control over their lives.


I suspect that using your brain (e.g. reading, going to school, university or college, having interesting hobbies) might also be good for it, but I can’t prove this as there is no evidence one way or another. Again developing interests is also fun and empowering.



  • I have a friend whose mom has Huntington’s disease and he has a 50% that one day he will one day develop the disease as well. How can I help him stay calm?

First of all I want to stress that living with the risk of HD and worrying about when symptoms may start is very common, so your friend is not alone.


As you probably know the average age of onset for developing HD is mid 30s to mid 40s so it is understandable that your friend is worried that he may begin to show signs in the next 10 years or so. But I also want to stress that even if someone knows they carry the gene  for HD from a predictive test currently we cannot accurately predict when Huntington’s disease will develop in an individual. The symptoms that individuals have can also vary in families. There can be a lot of myths and misunderstandings about HD so it is really important to get accurate information. I hope the information on this site will answer any questions you and your friends have about HD, but please just ask if there is anything else.


It might also be helpful for you and your friend to know that there is a lot of research being done into HD at the moment, and so there is a lot of hope. If you want to know more about current research we recommend you look at HDBuzz.


Another hugely important thing you can do to help, and it sounds you are doing already, is to encourage your friend to talk and share his feelings. Just having someone who listens on a regular basis, someone who is at the end of the phone (or text or Facebook) can be a real support, even if you are hundreds of miles away. You may not think that you are saying the right things, and hopefully some of the information on our site can help you, but just listening and being there can be a huge support.


You have also asked how can you help your friend to keep calm? Whilst having someone you trust to talk to is very important there are also lots of other strategies young people tell us they use to keep calm and manage their anxiety. In general this involves looking after yourself (so exercising, sleeping and eating well are all important) and doing things that help you to relax or stay focused e.g. running, listening to music, watching a film, keeping busy.


One of the main strategies young adults tell us they use is to get support, whether that is from friends, the HD community or professionals. For example, meeting other young adults in the same situation can be a huge help.


Some individuals also decide that they cannot live with the uncertainty and choose to take the predictive test for HD to know whether they carry the changed gene or not. If this is something your friend is thinking about he could make an appointment with a genetic counselor who would talk through the pros and cons of testing with him (also see our section on genetic testing).


It may be helpful to talk with a genetic counselor even if he does not want the test because one of their roles is to help people find strategies to manage the uncertainty of being at risk of serious genetic conditions. I also know some young adults who do not want the test, but who go for annual appointments with an HD specialist, for reassurance that they aren’t showing any signs and up to date information.



  • What makes people want to be tested for HD?

The question of whether or not to have testing for HD (I’m assuming you mean predictive testing?) is a very personal one. For many individuals at risk of developing HD the question also relates to timing and at what stage in their lives such information may or may not be useful.


There has actually been quite a lot of research on the question of what motivates people to be tested. We know that only about 10-20% of individuals at risk of HD, choose to have a predictive test. The main reasons put forward for testing include relief of uncertainty, needing to know and to help with decisions particularly around having children. Reasons for not testing include the fact that there is currently no cure and preferring to live with the 50% risk rather than risk the possibility of receiving a bad news result.



  • Is HD more common in specific genders or groups?

I’d like to deal with your question in to parts. The first is about gender and the answer is that HD is equally common in men and women.


The second question about groups is a bit more difficult. I think you are talking about ethnic groups (like Caucasian, Hispanic, African-American etc). The simple answer is that there is no clear difference between ethnic groups. The more complicated answer is that these groups are much more difficult to separate than gender groups (most people can be very easily identified as a man or woman!). We’re all of a mixed ethnicity really from the point of view of genetics. However, there are one or two parts of the world with very isolated populations which have a very high rate of HD (for instance, a small area in Venezuela and a part of the North West of Pakistan) but this only happens in areas that people don’t move in and out of very often.



  • Can I get tested before I’m 18?

If you can, try not to get too fixed on the question of predictive testing at 17 vs 18. In some ways this may miss the point – whether the information a predictive test would provide would be useful to you at this particular time? (this is not just a question for 17 year olds, but for adults of any age considering a predictive test). Most individuals need space to consider what is involved in testing, how they and their family would cope with the information a test would provide and whether a test is the best alternative for their particular circumstances.



  • I have two brothers. How many of us will get HD?

I am basing my answer on you and your siblings being at 50% risk with either your mum or dad having HD, or the changed gene. The truth is that we just don’t know between you and your brothers who may develop HD. It is possible that none of you could develop HD, or that one, two or all three of you could have the changed gene.


I often explain having, or not having, the HD gene as being like the flip of coin. Imagine heads is the HD gene and tails is the normal gene. You could flip the coin 3 times and it lands on heads every time thus meaning everyone will develop HD or it could be tails meaning no-one will develop HD or it could be a mixture of heads and tails meaning that some of you will have the gene and some of you won’t have the gene. Therefore no-one can say in any family how many people will have the gene, unless you undergo predictive testing when you reach the legal age to do so (18 in most countries), however this isn’t a decision to be taken lightly or rushed into.