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  #1  
Old 05-28-2011
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Genetics Autosomal Dominant Inheritance Question

Neurofibromatosis type 1 is one of the most common autosomal dominant disorders. A woman with neurofibromatosis type 1 has an unaffected partner. Which of the following is correct regarding their children?


a) The probability that each of their children will be affected is 1 in 4.
b) The probability that their second child will be affected if their first child is affected is 1 in 4.
c) The probability that their third child will be affected if their first two children are affected is 1 in 2.
d) If their first child is affected then their second child will not be affected.
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Old 05-28-2011
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its B i think
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Quote:
Originally Posted by Claus_CU View Post
Neurofibromatosis type 1 is one of the most common autosomal dominant disorders. A woman with neurofibromatosis type 1 has an unaffected partner. Which of the following is correct regarding their children?


a) The probability that each of their children will be affected is 1 in 4.
b) The probability that their second child will be affected if their first child is affected is 1 in 4.
c) The probability that their third child will be affected if their first two children are affected is 1 in 2.
d) If their first child is affected then their second child will not be affected.
I think is C)
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Old 05-28-2011
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i think its c
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Old 05-28-2011
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Yes, I think its C) because:

Female is heterozygous affected & male is homozygous normal.

That gives a 50% chance of each child having a heterizygous affected genes.
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Old 05-28-2011
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Quote:
Originally Posted by Claus_CU View Post
Neurofibromatosis type 1 is one of the most common autosomal dominant disorders. A woman with neurofibromatosis type 1 has an unaffected partner. Which of the following is correct regarding their children?


a) The probability that each of their children will be affected is 1 in 4.
b) The probability that their second child will be affected if their first child is affected is 1 in 4.
c) The probability that their third child will be affected if their first two children are affected is 1 in 2.
d) If their first child is affected then their second child will not be affected.
The correct answer is C). Thanks.
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Old 05-28-2011
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But in autosomal dominant condition,if male is normal and female is heterozyogous then 2 child will be affected while the remaining two will not be affected..isn't it like that?
So i think if first two children are affected then the other two will be normal..
Can anyone please explain it?:sorry:
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Originally Posted by struggle View Post
But in autosomal dominant condition,if male is normal and female is heterozyogous then 2 child will be affected while the remaining two will not be affected..isn't it like that?
So i think if first two children are affected then the other two will be normal..
Can anyone please explain it?:sorry:
When an affected individual has children, and the other partner is not affected, the probability that each child will be affected is 1 in 2. Even if you have a child that has the disease, the next child will have the same 50%/50% chance of having the disease.
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Old 06-07-2011
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C is correct.
Aa (Mother) * aa (Father) =
Children: Aa - Aa - aa - aa --> 1/2 of children are affected.
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