Pedigree Charts

Genetics as it applies to evolution, molecular biology, and medical aspects.

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Pedigree Charts

Post by greendaychic88 » Fri Feb 17, 2006 2:01 am

how do you do ratios for pedigree charts, and how do you do pedigree charts

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Re: Pedigree Charts

Post by zami'87. » Sun Feb 19, 2006 12:02 am

greendaychic88 wrote:how do you do ratios for pedigree charts, and how do you do pedigree charts

this should be moved to genetics thread :?

Classical problem:for example imagine that a guy and girl want a child. He has brother with some autosomal recessive disorder and a girl has a sister with the same disorder. Guy's parents and girl's parents don't show signs of disorder(so because of one affected child they're both carriers)
What is the probability that their child will be affected?
Draw a pedigree. Because guy's parents are healthy, he is healthy and his brother is affected then probability that a guy is a carrier of deffected allele is 2/3 because u can get [AA,Aa,Aa],aa The same case for girl(she has affected sister...) 2/3. Probability that 2 carriers will have affected child is (2/3)[guy's side]*(2/3)[girl's side]*(1/4)[2 carriers give affected child]=1/9
if one partner doesn't have signs of disease in family u can count on his side frequency of carriers 2pq in population.
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Post by mith » Sun Feb 19, 2006 2:29 am


Please read forum rules regarding posts

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