genetics question

[yahoogoogle]

Advertisement - Members don't see this ad

Imagine you are a genetics counselor, and a couple planning to start a family came to you for information. Charles was married once before, and he and his first wife had a child who has cystic fibrosis. The brother of his current wife Elaine died of cystic fibrosis. What is the probability that Charles and Elain will have a baby with cystic fibrosis? Neither Charles nor Elaine has cystic fibrosis.

answer is 1/6

 

[FlipAEPi]

can u please explain, i am getting 1/4 unless there is something I am not aware of.

 

[jeezy]

im assuming this is autosomal, not xlinked
N = normal
n = cystic fibrosis

guy = Nn
Womans parents and both Nn
so the woman has a 1/3 chance of being NN, or 2/3 chance of Nn

if shes Nn, they have a 1/4 chance of having a kid with CS
if shes NN, its not possible

(2/3 x 1/4) + (1/3 x 0) = 1/6

 

[tresbon]

im assuming this is autosomal, not xlinked
N = normal
n = cystic fibrosis

guy = Nn
Womans parents and both Nn
so the woman has a 1/3 chance of being NN, or 2/3 chance of Nn

if shes Nn, they have a 1/4 chance of having a kid with CS
if shes NN, its not possible

(2/3 x 1/4) + (1/3 x 0) = 1/6

Very sharp deduction. Excellent job, jeezy.👍