Huntingtons Disease

Question 1

def

Answer 1

inherited, incurable, progressive, neurodegenerative disorder

Question 2

what sort of genetic disorder is HD

Answer 2

autosomal dominant

Question 3

epi

Answer 3

middle age

men + women affected equally

Question 4

aetiology

Answer 4

huntingtin gene codes for protein huntingtin

the huntingtin gene has extended trinucleotide repeat expansion (CAG) which causes toxic gain of function

this abnormal protein damages the brain

Question 5

what is characteristic of the inheritance of the disorder

Answer 5

disease exhibits anticipation (earlier age of onset with each successive generation)

Question 6

what chromosome codes for the huntingtin gene

Answer 6

4p

Question 7

history

Answer 7

family history of huntingdons disease

insidious onset in middle age of progressive symptoms (irritability, depression, incoordination)
progression to chorea, dementia and/or fits

Question 8

what is chorea

Answer 8

neurological disorder characterised by jerky involuntary movements

Question 9

examination

Answer 9

classic presentation is with chorea and dysarthria
slow voluntary saccades
impaired coordination, unsteadiness, cognitive + emotional deficits

Question 10

what is dysarthria

Answer 10

unclear or slurred speech (mechanical problem)

Question 11

what are saccades

Answer 11

rapid, simultaneous movement of both eyes

Question 12

investigations

Answer 12

1 genetic analysis
-diagnostic if >39 CAG repeats in HD gene
2 imaging
-symmetrical atrophy of striatum + butterfly dilation of lateral ventricles

Question 13

what is the pathology of HD

Answer 13

atrophy + neuronal loss of striatum + cortex

particularly caudate nuclei