Ques 14 The pedigree below concerns a certain rare X-linked recessive disease th
ID: 193043 • Letter: Q
Question
Ques 14
The pedigree below concerns a certain rare X-linked recessive disease that is incapacitating but not fatal.
If you were doctor of the family shown in the pedigree above, how would you advise the three couples in the third generation about the likelihood of having an affected child?
Couple 1 has no chance of an affected child, couple 2 has a 50% chance of affected sons and no chance of affected daughters, and couple 3 has no chance of having affected children (but all daughters are carriers).Explanation / Answer
If I was the doctor of the family shown in the pedigree above. I would say:
For couple 1: there is no chance that the couple has an affected child.
For couple 2: There is a 50% chance that their sons are affected but the daughters won't be affected but all of them would be carriers.
For couple 3: there is no chance of having affected children (but all daughters are carriers).
So, the correct answer here would be, Option 1, which is the nearest.
"Couple 1 has no chance of an affected child, couple 2 has a 50% chance of affected sons and no chance of affected daughters, and couple 3 has no chance of having affected children (but all daughters are carriers)."