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14 Cards in this Set
- Front
- Back
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What causes Huntington's disease? |
- autosomal dominant condition - mutation of Huntingtin gene (HTT) - codes for Huntingtin protein - (short arm of chromosome 4) - causes increased decay rate of certain neurons in the brain |
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Genetics of Huntington's disease? |
part of Huntintin gene is a 'trinucleoside repeat' - Involves multiple repeats of 'CAG' - codes for glutamine - everybody has different numbers of repeats - if this number is too high however, the protein produced is defective |
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What effect does the number of CAG repeats have on the severity of Huntington's? |
≤35 repeats = normal 36-39 repeats = reduced penertance (late-onset Huntington's & slower progression) ≥40 repeats = full penetrance (early-onset Huntington's) ↑ repeats = ↑ severity |
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What is the function of the Huntingtin protein? |
upregulates expression of the 'brain derived neurotrophic factor' (BDNF) BDNF support neurons & helps growth of new neurons and synapses ↑CAG repeats = less functional Huntingtin protein = less expression of BDNF |
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What is juvenile Huntington's disease? |
Huntington's that is symptomatic before the age of 20 |
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What are of the brain is affected most in early Huntington's? |
striatum (caudate nucleus & putamen) |
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What causes the chorea in Huntington's? |
Damage to the basal ganglia - causes uncontrolled, erratic inhibition/ disinhibition of movements |
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What is the epidemiology of Huntington's?
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much more common in Europeans & North Americans ~ 1 in 15,000 in those populations |
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What symptoms would you expect in early Huntington's?
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- clumsiness* - behavioural/ personality changes* - concentration impairment* - balance/ gait diffculties - anxiety - irritability* - impulsivity |
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What symptoms might you expect in more advanced Huntington's?
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- chorea - parkinsonism - dementia - dysphagia - cognitive impairment - slowed rapid eye movement |
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How do you diagnose Huntington's disease?
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- CAG repeat testing - MRI may show striatal atrophy |
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What is tetrabenazine and when is it used? (mechanism of action)
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- Used to treat a range of hyperkinetic disorders reversible depletion of monoamines from nerve terminals: - dopamine - serotonin - noradrenaline prevents transport of monoamines into vesicles |
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What are the most common side effects associated with tetrabenazine in Huntington's patients?
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- depression/ suicidal thoughts - sedation |
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What is the average life expectancy from the point of diagnosis in Huntington's?
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20 years |
