Huntington's Disease Flashcards
What is the definition of Huntington’s disease?
An autosomally dominant trinucleotide repeat disease characterised by progressive chorea (abnormal involuntary movement) and dementia, typically commencing in middle age
What is the aetiology / risk factors involved with Huntingtons disease?
- The huntingtin gener (HTT) codes for huntingtin protein (HTT)
- In the HTT gene there’s a trinucleotide repeat expansion (CAG) that results in toxic gain of function
- IT IS AUTOSOMALLY DOMINANT
- Has an earlier age of onset with each successive generation
Summarise the epidemiology of Huntingtons disease
Average age of onset = 30-50 yrs old
What are the presenting symptoms of Huntingtons
- Family history
- INSIDIOUS onset in middle-age
- Progressive
- Fidgeting
- Clumsiness
- Involuntary, jerky, dyskinetic movements often accompanied by grunting and dysarthria
What are the early cognitive changes present in Huntingtons?
- Mood lability
- Dysphoria (a state of unease or generalised dissatisfaction with life)
- Mental inflexibility
- Anxiety
- Develops into dementia
What changes occur in the later stages of Huntingtons?
Rigid
Akinetic
Bed-bound
What is important to ask about in the history of a patient with suspected huntingtons?
Enquire about drug history (especially cocaine and anti-psychotics)
What signs are present on physical examination of someone with Huntington’s?
- Chorea
- Dysarthria
- Slow voluntary saccades
- Supranuclear gaze restriction
- Parkinsonism
- Dystonia
- MMSE shows cognitive and emotional deficits
What investigations are appropriate for a patient with suspected Huntingtons
Genetic Analysis
- Diagnostic if there are > 39 CAG repeats in the HD gene
- Reduced penetrance leads to an intermediate number of CAG repeats
Imaging
- Brain MRI or CT may show symmetrical atrophy of the striatum and butterfly dilation of the lateral ventricles
Bloods
- To exclude other pathology
