Consider the pedigree below showing a rare (not commonly found in the population

Question

Consider the pedigree below showing a rare (not commonly found in the population) X-linked recessive trait. Assume no spontaneous mutations in this family and 100% penetrance. In the first generation, the man is unaffected and the woman is affected. Individuals indicated by letters in subsequent generations may or may not be affected. Choose your answer(s) carefully since you will receive credit only if you select all possible correct answers. If this rare trait were an X-linked DOMINANT that causes death before birth when homozygous, which individuals have a 50% chance of being affected? If none of the individuals have a 50% chance of being affected, then select "Q". A B C D E F G H I J K L M N O P Q

Explanation / Answer

Individuals with 50% chance of being affected by X-linked dominant trait- B, C, D, E.

The father is unaffected and mother is affected. Since homozygous condition with the gene results in death before birth, the only possible genotype is XaXA (where A represents the dominant gene and a is the normal allele). So, the sons of the couple (C, E) will get Y from father and can get either Xa or XA from the mother. Hence, the chance of being affected will be 50%. Similarly, the daughters will get normal Xa from father and can get either Xa or XA from the mother. Hence, the chance of being affected will be 50%.

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.