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What if BOTH parents have Huntington's Disease?..

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mhwebb03
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Jan12-09, 05:16 AM
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I know that if one parent has HD then there is a 50% chance that their child will inherit the disease. Because lets say H represents the dominant allele (bad) for HD.. and h represents the recessive (normal).. If one parent (Hh) carries the disease, and the other (hh) doesn't have the disease, and they have a child.. Then by use of a punnett square we can determine that the probability of getting Hh offspring is 50% and the probability of getting hh offspring is 50%. (probability of getting HH is 0%)..

okay.. but WHAT IF.. TWO people who had Huntington's had kids? then you'd potentially be looking at Hh x Hh, so there would be a 50% chance of Hh in offspring, 25% HH, 25% hh. so 25% normal. I want to know about the HH. please anybody tell me about the HH. I assume that means yes, you get the disease.. But does it progress worse and cause an earlier death or what?. I'm having trouble finding information.

If you got both dominant H's, and just having one gave you an excess of CAG sequences.. Then would that mean you'd just have a lot more CAG sequences, which IS supposed to mean that the disease is more extreme and probably more immediately fatal.
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Monique
#2
Jan12-09, 06:55 AM
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Research suggests that the age of onset appears to be the same, but the rate of disease progression is faster.

"Homozygosity for CAG mutation in Huntington disease is associated with a more severe clinical course"
http://brain.oxfordjournals.org/cgi/...full/126/4/946


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