Lecture 1- Huntington's Disease

Question 1

What is chorea

Answer 1

Involuntary motor movements

Question 2

What is Dystonia

Answer 2

Prolonged contraction in abnormal position

Question 3

What is dysarthria

Answer 3

Reduction of speech

Question 4

What is bradykinesia

Answer 4

Slowness of movements

Question 5

Give examples of Huntington’s disease symptoms to do with movement

Answer 5

Chorea
Dystonia
Bradykinesia
Dysarthia

Question 6

Give examples of Huntington’s disease symptoms to do with mood

Answer 6

Depression 
Euphoria 
Apathy 
Anxiety 
Aggression 
Psychotic symptoms

Question 7

Give examples of Huntington’s disease symptoms to do with memory

Answer 7

Loss of executive functioning
Dementia
Memory loss
Rigidity of thought

Question 8

What is the mean age of onset of Huntington’s disease

Answer 8

35-44 years

Question 9

What is the range of onset of Huntington’s disease

Answer 9

2 - 80 yrs

Question 10

Median survival time of Huntington’s disease

Answer 10

15 to 18 yrs after onset

Question 11

Is Huntington’s disease recessive or dominant

Answer 11

Autosomal dominant

Question 12

Does Huntington’s disease have complete or incomplete penetrance

Answer 12

Complete

Question 13

A mutation in which gene causes Huntington’s disease

Answer 13

HTT gene

Question 14

What is the mutation in the HTT gene that causes Huntington’s disease

Answer 14

Normally, CAG trinucletoide repeat is repeated 10 to 35 times within the HTT gene
In Huntington’s- CAG is repeated 36 to 120+ times

Question 15

How does a mutation in the HTT gene disrupt the normal function of neurons

Answer 15

Increase in size of CAG segment =
Production of abnormally long Huntington protein =
Elongated proteins are cut into smaller, toxic fragments that bind together =
Accumulate in neurons and disrupt their cells functioning

Question 16

What part of the HTT gene are CAG (cytosine adenine guanine) repeats present

Answer 16

Within exon 1

Question 17

In a normal gene how many CAG repeats are present

Answer 17

Less that 36

Question 18

In a mutated gene causing Huntington’s, how many CAG repeats are present

Answer 18

40 or more

Question 19

What amino acid does CAG code for

Answer 19

Glutamine

Question 20

What does polyglutamine (polyQ) expansion altering protein structure/ properties and aggregating in cells primarily affect

Answer 20

Basal ganglia, especially caudate nucleus

Question 21

What causes a younger age of onset of Huntington’s disease

Answer 21

More CAG repeats (also causes more severe symptoms usually)

Question 22

Does paternal or maternal inheritance carry a higher anticipation risk of Huntington’s disease

Answer 22

Paternal inheritance

Question 23

What is anticipation

Answer 23

Onset occurs at earlier age as it is passed from one generation to the next

Question 24

How is juvenile HD usually inherited

Answer 24

Paternally

Question 25

What age of onset is classed as juvenile Huntington’s disease

Answer 25

Less than 20 years

Question 26

What causes anticipation of Huntington’s disease in terms of the gene

Answer 26

The triplet repeat expansions are unstable and might increase or contract when passed to the next generation - not common

Question 27

What is predictive testing

Answer 27

Genetic test in someone who’s asymptomatic but at risk to predict the future of disease