Huntington's Disease

Question 1

What is HD?

Answer 1

Progressive neurodegenerative disorder with motor, cognitive and psychiatric disturbances

Question 2

Examples of movement disorders

Answer 2

Chorea (jerky), dystonia (abnormal muscle tone), bradykinesia, swallowing/choking, dysarthia (articulation of speech)

Question 3

Examples of mood disorders

Answer 3

Depression, euphoria, apathy, anxiety, aggression, psychotic symptoms

Question 4

Examples of cognitive disorders

Answer 4

Loss of executive functioning, rigidity of thought, memory loss, dementia

Question 5

Age of onset of HD

Answer 5

35 - 44
(range 2-80 years tho)
Median survival time is 15-18 years after onset

Question 6

HD inheritance type and penetrance

Answer 6

AD

Complete penetrance

Question 7

Which gene is HD?

Answer 7

HTT gene at 4q16.3

Normal HTT gene contains, within exon 1, a run of CAG repeats >40 = HD mutation

Question 8

What is the abnormal protein coded by … for HD

Answer 8

Coded by HHT gene
Increased number of glutamine amino acids = polyO expansion which alters protein structure and biochemical properties.

PolyO cellular protein aggregates form - unknown if they cause disease. Basal ganglia especially caudate nucleus primarily affected

Question 9

Anticipation and HD

Answer 9

High anticipation risk if paternal inheritance.

More CAG repeats the lower the age of onset