Huntington's Disease

Question 1

What is chorea?

Answer 1

an abnormal involuntary movement disorder, characterized by continuous, abrupt, rapid, brief, jerky, irregular movements that flow randomly from one body part to another

Question 2

what can cause chorea

Answer 2

movement disordered associated with pathological changes in the brain especially the basal ganglia

Question 3

what sickness leads to Sydenham chorea

Answer 3

rheumatic fever or strep throat

Question 4

in what populations is HD more prevalent

Answer 4

white, 7-10 cases per 100,000

Question 5

describe the hunting gene

Answer 5

-located in exon 1 on short arm of chromosome 4
-consist of an expanded trinucleotide repeat CAG

Question 6

how many CAG repeats will a patient need to be diagnosed positive for HD

Answer 6

40 or more

Question 7

what type of inheritance is HD

Answer 7

autosomal dominant
50% chance

Question 8

describe anticipation with HD

Answer 8

more CAG repeats associated with increased severity and earlier age of onset

Question 9

does expansion and anticipation occur more often with maternal or paternal transmission?

Answer 9

paternal

Question 10

describe the huntingtin protein

Answer 10

-350 kDa containing polyglutamine sequence at the NH2 terminus
-cytoplasmic
-highest levels in the neurons of CNS

Question 11

what are the physiological functions of the huntingtin protein?

Answer 11

-necessary for embryonic development
-acts as a protein scaffold
-serves as transcriptional regulator
-plays important roles in synaptic connectivity

Question 12

describe juvenile HD

Answer 12

-westphal variant: age of onset less than 20
-5-10% of HD cases
-typically paternal transmission
-initial features (personality, parkinsonism, bradykinesia, rigidity, dystonia)
-later features (dementia, dysarthria, abnormal eye movements, tremor, seizures)
-5-15 years of illness
-more than 50 CAG repeats