new_dream77
Forum Newbie
Topics: 5
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50yr old man who had M.I later diagnosed as havin hypercholesterolemia,an autosomal dominant disorder.his son has not being tested for hypercholesterolimia,whts probability tht patients granddaughter thrro'his son will have hypercholestelorimia?
A less than 1%
B 10%
C 25%
D 33%
E 50%
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| GMOB
Forum Elite
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I think E. 50% I am not sure. but as autosomical dominant, only one gene needs to be present for the disease. The son might be heretogynous (Aa) if he marries a normal person (aa) and you do a crossing, then the chances of the baby being Aa are 50%. I dont know if this is right...
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| ssrpk
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yeah for one generation it is 50% but for two generations u need to multiply the independent probabiliuties together! (joint probabilities for independent events)
so 0.5 X 0.5 = 0.25
answer is c
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| GMOB
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thanks!
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| 99doc
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i don't get it.
how do we know the son ever had a defective gene,his father might have been heterozygous?
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| ssrpk
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in AD, heterzygtes will show phenotypic exprssion of the disease as wel!
anyway this q is asking aboyut the assumption of the carrier frequency in two successive generations in a row, ofcourse anything is possible but wht is the probability tht the son and then the granddaughter will both inherit the defective genes- "joint probabiulities of independent events"
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| ssrpk
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if u are still having problems u can chkeck outr the details about these probabilities in the biostatistics section!
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| 99doc
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Thanx,i will check it.
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