Question

Assuming that it is not a Y-linked trait, suggest the most likely mode of inheritance for the rare trait shown in the pedigree below.

a. Autosomal recessive
b. Autosomal dominant
c. X-linked recessive
d. X-linked dominant
e. Mitochondrial

Answer 1

The most likely mode of inheritance for the rare trait described in the pedigree is X-linked recessive, which accounts for the pattern where males are more frequently affected and females can be carriers without being affected.

Step-by-step explanation:

To determine the most likely mode of inheritance for the rare trait in the given pedigree, several key considerations are examined. First, if the trait is not Y-linked, this eliminates Y-linked inheritance. Next, the description given in the question aligns with an X-linked recessive pattern, where male offspring have a 50 percent probability of being affected if the mother is a carrier, and female offspring would be either carriers or unaffected, given the normal gene from the father.

This is further supported when compared to autosomal inheritance, where autosomal recessive traits would require two carrier parents for the trait to be expressed in offspring, and autosomal dominant traits would appear in every generation if a parent is affected. Since the question specifies a rare trait and X-linked recessive traits are known to affect males more frequently due to their single X chromosome, X-linked recessive inheritance is the most likely mode of inheritance for the described trait.