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Huntington's Disease 2


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What is the inheritance pattern for Huntington's Disease?
autosomal dominant with anticipation
HD is due to an expansion of the ________ gene on chromosome ____.
huntington; 4
T/F: HD demonstrates a low degree of penetrance
Signs/Symptoms of HD
chorea (cardinal manifestation)
behavioral and personality disorders
HD has been hypothesized to result from a ___ of function mutation.
All individuals who have the HD mutation will manifest the disease by the time they are ___ years old, with 50% of HD patients expressing their symptoms by age __.
80; 45
What are the symptoms of Juvenile HD?
rigidity, tremor, dystonia, myoclonic epilepsy, dementia
HD patients have an expanded _ _ _ allele.
An individual with __ or more repeats will likely develop HD sometime in their life.
Someone with fewer than __ repeats will not likely develop HD.
What are some non-translated trinucleotide repeat disorders?
Fragile X & Myotonic dystrophy
What are some translated trinucleotide repeat disorders?
Spinobulbar muscular atrophy (Kennedy syndrome)
Spinocerebellar ataxia (type 1 & 7)
Dentatorubropallidoluysian atrophy (DRPLA)
Expanision of repeats in HD occurs in ___________ transmission.
What area of the brain is most affected by HD?
What part of the brain (specifically) is affected earliest in HD?
the tail of the caudate
What kind of neurons are lost in the caudate and putamen in HD?
medium spiny neurons
In what order are the types of medium spiny neurons lost in HD?
1st: enkephalinergic neurons
2nd: Substance P neurons (lost only later in disease)
The striatum excites the globus pallidus via which pathway?
indirect (direct inhibits)
The enkephalinergic neurons in the striatum project to the globus pallidus via the direct or indirect pathway?
What is the simplified pathway of basal ganglia circuitry involved HD?
cerebral cortex excites striatum -->
striatum inhibits medial globus pallidus (via direct or indirect pathway) -->
project to thalamus -->
projects back to cortex
Is the pathway from the cortex to the basal ganglia excitatory or inhibitory?
In HD there is a preferential loss of neurons to the _________.
lateral globus pallidus
T/F: In Juvenile HD there is a preferential loss of neurons to the medial globus pallidus.
False: in Juvenile HD there is equal loss to lateral and medial globus pallidus
What are two hypotheses about HD pathophysiology?
1. excitatory amino acids are involved
2. mitochondrial energy metabolism may contribute to nerve degeneration
In what tissue is the protein that the huntington gene encodes found?
all tissue
Where in the cell is the protein encoded by the huntington gene found?
Do HD brains show an increase or decrease in the huntington protein?
What are some potential therapies for HD (demonstrated in mouse models)?
ciliary neurotrophic factor
environmental enrichment
How many CAG repeats does a normal person have?
less than 26
What are some current treatment options for chorea?
Benign neglect is best
occupational and physical therapy
speech therapy
medications (atypical antipsychotics, amantidine, tetrabenazine)

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