Huntington Disease Flashcards
Describe Genetic Anticipation.
Future generations may be affected earlier because polyQ can expand and get bigger. A parent with incomplete penetrance (36-40 repeats) may pass on a copy with increased number of repeats, resulting in a child with fully penetrant HD and since instability is greater in spermatogenesis, it is more likely a paternally inherited HD.
Which sex is more affected by HD?
Both equally affected
What chromosome contains the Htt gene?
4p
Where do you see neuronal loss in Huntington disease?
Basal ganglia and cerebral cortex
What is the polymorphic trinucleotide repeat that causes large polyglutamine repeats?
CAG
What is the relationship between time of onset and number of repeats?
More repeats = Earlier onset
If less than 35 repeats, what is your risk of transmission to offspring?
No risk
If 35-40 repeats, 40 to 60 repeats, or over 60 repeats, what is your risk of transfer to offspring?
50 % risk
What is the most common age of onset?
35-50
What are the neurodegenerative symptoms of Huntington disease?
Chorea, psychiatric disturbances, cognitive impairment.
You have to have more than what number of repeats to have full HD penetrance?
40
Over exposure to Glutamate in HD patients causes what receptor to be lost in the putamen?
NMDA receptor
What makes up the striatum?
Caudate, putamen, nucleus accumbens
What does the poly Q repeat do to the Huntingtin protein?
Makes it insoluble and it aggregates
What do you stain for to find the Huntingtin protein?
Ubiquitin