A 9 year old boy with normal parents has hemophilia. His full sister is pregnant.
What is the probability that she will have a child with hemophilia?
Re: Can you answer this genetics question?!
You need a bit more info really.
I would assume for the boy to be homozygous for heamophillia both the parents must be hetrozygous, that means the sister could either be hetrozygous or not a carrier at all.
If we assume the sister is not a carrier at all and the babies dad is not a carrier then the probability would be 0.
If the sister is hetrozygous like the parents and the babies dad is not a carrier there will be a 0 chance of having heamophilia but a 1/4 chance of been a carrier.
If the sister has heamophillia but the babies dad is not a carrier then there is a 0 chance of having heamophilia but 1/2 chance of been a carrier.
It's going to depend on the status of the babies father.
I think that would be the right but it has been 10 years since I did this so wait for other answers.
Re: Can you answer this genetics question?!
^Actually I posted it as a fun quiz to see if anyone can solve it.
Here are some hints. Hemophilia is an X-linked recessive disease. And it's a rare one. So, since it's rare, one must assume that subject in question marries a normal person.
Ok, that's it for hints :)
Re: Can you answer this genetics question?!
here’s my hemophilia worksheet: http://www.sendspace.com/file/8exqz3
I have done the work but haven’t given the probability for the daughter of normal parents producing hemophilic offspring…thats for you to figure out based on the punnet squares i developed
basically it starts out like this:
hemophilia is an x-linked disease so…the father cant even be a carrier, the mother however must be a carrier if the mating of said “normal” parents has produced one child with hemophilia
if you do a punnet square of a normal father (XY) with a carrier mother (XhX) you get 25% of their daughters will be carriers of hemophilia and 25% of her sons will be hemophilic
so then to figure out whether their daughter will produce hemophilic offspring you have 4 cases:
Case 1: if the daughter was carrier of hemophilia(XhX) and she mated with a man who was normal(XY)
result= 25% chance she will have a child with hemophelia
Case 2: if the daughter was carrier of hemophilia(XhX) and she mated with a man who was hemophilic(XhY)
result=50% chance she will have a child with hemophelia
Case 3: normal daughter(XX) and she mated with a man who was hemophilic(XhY)
result=No hemophilic children
Case 4: normal daughter(XX) and she mated with a normal man(XY)
result=No hemophilic children
only case 1 and 4 are most probable as hemophelia is a rare disease
Re: Can you answer this genetics question?!
^Good work llxxll, I'm tempted to post the final answer but will wait for someone to get to it. The final answer is just one (after having taken all the 'ifs' into account)
Re: Can you answer this genetics question?!
oh bummer I did not realise heamophilia was a sex linked
Re: Can you answer this genetics question?!
27.945%
Re: Can you answer this genetics question?!
The answer is 0, if the babies father is not a carrier then there is no way the baby will have heamophilia. At most the baby will be a carrier.
Re: Can you answer this genetics question?!
The answer is 12.5% or 1/8
The brother has hemophilia. So this makes him X(h) Y
This implies that the mother of this boy must be a carrier: X(H) X(h) and therefore, a carrier, but normal as stated.
The father of the boy was stated to be normal, which means he is: X(H) Y
Therefore, their daughter (pregnant female) should be either X(H)X(H) or a carrier X(H) X(h). Therefore, she has a 0.5 chance of being a carrier.
IF she is a carrier, then the probability that she will have a child with hemophilia is 1 in 4: 0.25
Multiply the p(pregnant female is a carrier) * p(child with hemophilia) to get total probability of her having a child with hemophilia:
0.5 * 0.25 = 12.5%
Re: Can you answer this genetics question?!
u knew the answer phir tumne itna kaam karvaaya:mad:
n here i thot u needed hw help 