Huntington’s disease is an illness caused by a faulty gene in your DNA (the biological ‘instructions’ you inherit which tell your cells what to do). If you develop symptoms of Huntington’s and are diagnosed with the disease before the age of 21, this is known as Juvenile Huntington’s disease - sometimes called JHD or Juvenile-onset Huntington’s.
Juvenile Huntington’s is quite rare. Less than 10% of people with the disease will have Juvenile-onset. This can make dealing with it quite an isolating experience for you and your family, and meeting others in the same situation can help.
People with Juvenile Huntington’s often experience some symptoms that are quite different from adult Huntington’s. If you have it, you are less likely to have the involuntary movements (making movements you don’t want to make), known as chorea. But you’re more likely to experience muscle contractions and stiffness, making the movements you do want to make slower and more difficult. You may also develop epilepsy (seizures).
Mood changes, such as feeling frustrated or angry and finding it hard to manage your behaviour, also seem to be a more common symptom in people who develop Huntington’s in their teens. This can often be the first sign of the illness, as can doing less well at school. However many children and young people with Juvenile Huntington’s do not have behavioural problems. And it’s important to remember that these symptoms may relate to other causes and not be due to Huntington’s.
These are just a few of the possible symptoms - you may not experience them all or you may experience different ones. There are many different kinds of help and support available to reduce symptoms and their effect on your life.