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I think this Q is not completed...I found a complete one from other posts
Here you go:
A young couple presents to ur office seeking prenatal counseling. The husband suffers from cystic fibrosis and is very concerned that his child will get the disease. The family pedigree is shown that
(husband and wife both are cousins and their parents didn't manifest the disease but one of his wife's sister got the disease..))
what is the chance that this child will get the disease?
A. 1/16
B. 1/8
C. 1/4
D. 1/3
E. 2/3
F. 3/4
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Here is the answer:
1/3 is the answer..
Since cystic fibrsis is an autosomal recessive disease and males always transmit the disease so chances of transmitting this disease to offspring is 100% or probability is 1..
mother's parents didnt manifest the disease but one of her sibling got the disease so her chances of getting the carrier gene is 2/3..(as in autosomal diseases if mother and father both are carrier, 25% of offsprings will manifest the disease,50% will be carrier and 25% will be homozygous normal..so as one of her sibling got the disease,out of the remaining 3 sibling,2 will be carrier,,so probability is 2/3))..
the chance that she will transmit the carrier gene to her child is 50% or 1/2..
so multiplying all..
1*2/3*1/2 =1/3..
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Thanks Maryam ! Now the answer should be 1/3.
Husband : aa
Wife : probabilty if being Aa is 2/3 ( coz her parents were Aa )
probability that she will tranfer "a" to the child : 1/2
Therfore child being 'aa' : 1/2 * 2/3...gives 1/3
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the que is from uw,check genetics section.
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@likewtf : the probability of wife being Aa is 2/3. Now assuming she is Aa, she will either transfer 'A' to the child or 'a'. So 50% chances that she will tranfer 'a', and that is 1/2. Hope you get it !
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okay guys this might be a very stupid question..
but i am still going to ask
AA- dominant
Aa- recesssive
aa-homo recessive
if her parents are carrier meaning they are Aa and she her self is a carrier so she is also Aa
her husband who has CF would be aa
his wife would is a carrier 2/3 ( 50% Aa and 25% AA)
chances her kid will get it 1/2 and mom 2/3 and dad 1
1/2*2/3* 1= 1/3
is that right?
