Hemophilia- X-linked Recessive- Punnet square help!

osi2011 · Jul 23, 2014

If I am not mistaken, the father can not be a carrier but actually has the disorder because men have only one x gene of which either carries a mutation or not, so if he has the mutation then he has the disorder. The mother on the other hand could be a carrier or have the disorder because she has two x genes. In this scenario, she has the disorder (both If her x genes carry the mutation) therefore all children will have the disorder because the x genes inherited from the parents carry the mutation. ....if you do a punnett square, you will be able to visualize it....hope this helps

JustBeachyNurse, LPN · Jul 23, 2014

Dad cannot be a carrier. Only females can be carriers of x-linked traits.

so say XH is the x-linked hemophilia. Xh is not.

Mom is carrier. XH Xh dad cannot be a carrier he has hemophilia or not.

Say dad does not so he is Xh Y.

Possibilities are: 1 XH Xh (carrier daughter), 2 XH Y Xh (son with hemophilia 3 Xh Xh (daughter without trait or hemophilia ) 4 XhY (son without hemophilia)

So in your scenario the possibility is zero since it's not possible for father to be a carrier.

If mom has hemophilia and dad has hemophilia it is 100% that sons and daughters would have x-linked hemophilia (XH XH + XH Y = XH XH. XH Y. XH XH. XH Y

If mom has hemophilia and dad does not then 100% sons will have hemophilia and 100% daughters will be carriers.

If mom is not a carrier and dad has hemophilia 0% boys have hemophilia and 100% girls carrier

If mom carrier and dad has hemophilia then 50% boys hemophilia 50% boys not 50% girls carrier 50% girls have hemophilia

smf0903 · Jul 23, 2014

Hm, sort of a bogus question. The only way father could be a carrier would be if he had Klinefelter's.

osi2011 · Jul 23, 2014

I believe the fact that the question mentions the father as a carrier, throws people off....either a tricky question or maybe it is not written well?

nurseprnRN, BSN, RN · Jul 23, 2014

No, if mother has hemophilia, she must have both of her two X chromosomes for hemophilia. If she only had one, she'd be a carrier but would not have the disease.

If father's a "carrier" his X has it (but of course, that means he's not a carrier, he has the disease, because he has no other X to override it).

Therefore, any child the hemophiliac mother has with this man, male or female, will have hemophilia. Girls, because the X they get from each parent has the hemophilia gene, and boys, because the only X they get is the one from the mother that carries the hemophilia gene.

That's why the answer is 100%.

Nursing2102 · Jul 24, 2014

I think my professor messed up on this question. I am gonna have to ask about it tomorrow. I think she meant "Mother is carrier, dad has it"

Just A Wanderer · Jul 24, 2014

^ I was thinking the same thing since men cannot be carriers, only affected by hemophilia. Although I read somewhere that females can still have hemophilia, albeit it's very rare?

smf0903 · Jul 24, 2014

I think my professor messed up on this question. I am gonna have to ask about it tomorrow. I think she meant "Mother is carrier, dad has it"

If that's the case then it's not 100%, it's only 50% chance overall.

Mom carrier XA Xa (a=recessive=hemophilia A=dominant=no hemophilia)

Dad affected Xa Y

XA Xa

Xa XAXa XaXa

Y XAY. XaY

(This is my punnett which refuses to cooperate as far as spacing LOL...bold are the mom and dad, regular font is the offspring possibilities)

XAXa-->carrier female

XaXa-->affected female

XAY-->unaffected male

XaY--->affected male

:)