Lecture 1- Huntington's Disease Flashcards
What is chorea
Involuntary motor movements
What is Dystonia
Prolonged contraction in abnormal position
What is dysarthria
Reduction of speech
What is bradykinesia
Slowness of movements
Give examples of Huntington’s disease symptoms to do with movement
Chorea
Dystonia
Bradykinesia
Dysarthia
Give examples of Huntington’s disease symptoms to do with mood
Depression Euphoria Apathy Anxiety Aggression Psychotic symptoms
Give examples of Huntington’s disease symptoms to do with memory
Loss of executive functioning
Dementia
Memory loss
Rigidity of thought
What is the mean age of onset of Huntington’s disease
35-44 years
What is the range of onset of Huntington’s disease
2 - 80 yrs
Median survival time of Huntington’s disease
15 to 18 yrs after onset
Is Huntington’s disease recessive or dominant
Autosomal dominant
Does Huntington’s disease have complete or incomplete penetrance
Complete
A mutation in which gene causes Huntington’s disease
HTT gene
What is the mutation in the HTT gene that causes Huntington’s disease
Normally, CAG trinucletoide repeat is repeated 10 to 35 times within the HTT gene
In Huntington’s- CAG is repeated 36 to 120+ times
How does a mutation in the HTT gene disrupt the normal function of neurons
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
What part of the HTT gene are CAG (cytosine adenine guanine) repeats present
Within exon 1
In a normal gene how many CAG repeats are present
Less that 36
In a mutated gene causing Huntington’s, how many CAG repeats are present
40 or more
What amino acid does CAG code for
Glutamine
What does polyglutamine (polyQ) expansion altering protein structure/ properties and aggregating in cells primarily affect
Basal ganglia, especially caudate nucleus
What causes a younger age of onset of Huntington’s disease
More CAG repeats (also causes more severe symptoms usually)
Does paternal or maternal inheritance carry a higher anticipation risk of Huntington’s disease
Paternal inheritance
What is anticipation
Onset occurs at earlier age as it is passed from one generation to the next
How is juvenile HD usually inherited
Paternally
What age of onset is classed as juvenile Huntington’s disease
Less than 20 years
What causes anticipation of Huntington’s disease in terms of the gene
The triplet repeat expansions are unstable and might increase or contract when passed to the next generation - not common
What is predictive testing
Genetic test in someone who’s asymptomatic but at risk to predict the future of disease
