Huntington's Disease

Question 1

Define Huntington’s Disease

Answer 1

Slowly progressive neurodegenerative disorder characterised by chorea, incoordination, cognitive decline, personality changes and psychiatric symptoms -> immobility, mutism + inanition

Rigid form: children/young adults with rigidity (may not have chorea) = early onset

Choreic form: Patients have chorea as a significant initial presenting feature. Most common type

Question 2

Aetiology of Huntington’s Disease

Answer 2

Expand CAG repeat at the terminus of the gene that codes for the Huntington protein
Primarily affects the striatum, with most clinical features directly attributable to damage in this area

Question 3

Epidemiology of Huntington’s Disease

Answer 3

Affects men and women equally
Typical onset 35-45
10x more common in North Americans of European descent

Question 4

Symptoms of Huntington’s Disease

Answer 4

Impaired work or school performance
Personality change
Irritability and impulsivity
Twitching or restlessness
Concentration impairment/task anxiety or apathy
Cognitive decline relative to spouse/siblings
Changes in personal habits/hygiene
Disinhibition or unusually anxious behaviour, depression, obsessions, compulsions
Dysphagia

Ask for FAMILY HISTORY

Question 5

Signs of Huntington’s Disease on examination

Answer 5

Chorea
Twitching or restlessness (athetosis)
Loss of coordination 
Deficit in fine motor coordination (apraxia)
Slowed rapid (saccadic) eye movements
Motor persistence 
Impaired tandem walking

Question 6

Investigations for Huntington’s Disease

Answer 6

CAG repeat testing: >40 CAF repeats - virtual certainly that symptoms will develop (<28 is normal)

MRI/CT