Question

Mr X is haemophilic and carrier of PKU. What percent of sperms posses defective allele for both trait

Answer 1

Hy,
Haemophilic is a sex linked disorder, means X chromosome is linked with it.
On the other hand, PKU will appear when both autosomal recessive combines.
Here, he's carrier so, PKU gene is affected.
The gene is XY since he's sufferer of hemophilia, it wil be X'Y. Also, he's carrier of PKU, the child will be sufferer of PKU, if his wife is also carrier of PKU.
Regarding hemophilia,
The cross here also depends on the partner
Supposing partner is normal, XX
The cross will be, X'Y × XX= X'X, X'X, XY, XY
The males will not be affected. The females will be carriers.
In second situation, let the female be carrier, X'X
The cross becomes,
X'Y×X'X = X'X', X'X, X'Y, XY.
Here you can see that 25%chances of male being sufferer, 25%chances of female being carrier, 25% chances of female being sufferer nd 25%chances of the individual being normal.
Hope it helps.
Regards
Dr Chinmay
Thanks

Answer 2

Hy,

Haemophilic is a sex linked disorder, means X chromosome is linked with it.

On the other hand, PKU will appear when both autosomal recessive combines.

Here, he's carrier so, PKU gene is affected.

The gene is XY since he's sufferer of hemophilia, it wil be X'Y. Also, he's carrier of PKU, the child will be sufferer of PKU, if his wife is also carrier of PKU.

Regarding hemophilia,

The cross here also depends on the partner

Supposing partner is normal, XX

The cross will be, X'Y × XX= X'X, X'X, XY, XY

The males will not be affected. The females will be carriers.

In second situation, let the female be carrier, X'X

The cross becomes,

X'Y×X'X = X'X', X'X, X'Y, XY.

Here you can see that 25%chances of male being sufferer, 25%chances of female being carrier, 25% chances of female being sufferer nd 25%chances of the individual being normal.

Hope it helps