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teddyusa
Forum Newbie Topics: 1 Posts: 8 
A man who has Neurofibromatosis type 1 (autosomal dominant) marries a phenotypically normal woman. If they have five children, what is the probability that none of the children will be affected with this disorder? What is the probability that all of the children will be affected? please explain the answer. Thanks  
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Ancylostoma
Forum Guru Topics: 43 Posts: 632 
Typical mating involving a autosomal dominant disease consists of a partner with one dominant allele, and one recessive. The lady is phenotypically normal so she has two recessive alleles. Now make a punnet square and you will see that within the square there are 4 possible outcomes. 2 affected(or carrying disease carrying gene) and 2 normal. Now you can figure out that there is a 50 percent chance of kid being affected each birth. Now the law of independent events says that if two outcomes( births) are independent and do not effect eachother then you can simply multipy the outcomes and get your probability. This is probability theory, you may need to get a math book if your not good with it and check it out a little. Now you have 5 seperate events, 5 births of children. probability of 1 child being affected 50% or .5 , probability of 2 .5 * .5 , probability of 5 affected .5 *.5*.5*.5*.5= .03125, rounded the probability that all 5 affected is 3.1% Thats the logic, like i said you amy need to look up the theory behind probablity to understand it better.  
teddyusa
Forum Newbie Topics: 1 Posts: 8 
Nice explanation Thanks, got it! Apreciate your help.  
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