Question

what kind of trait is illustrated in the diagram?
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a. sex - linked recessive
b. autosomal recessive
c. sex - linked dominant
d. autosomal dominant

Explanation:

• Autosomal dominant traits often appear in every generation. In the pedigree, affected individuals have at least one affected parent (assuming complete penetrance).
• Sex - linked recessive traits would show more affected males in a population (since males have only one X - chromosome). But here, both males and females are affected in a pattern that is more consistent with a dominant inheritance.
• Autosomal recessive traits usually skip generations. If it were recessive, we would expect to see more cases of unaffected parents having affected children (both parents being carriers).
• Sex - linked dominant traits are less common. Also, the pattern of inheritance in the given pedigree (where affected individuals have an affected parent and the trait is not showing a strict sex - bias in a way that would be typical for sex - linked dominant, and is more in line with autosomal dominant where males and females can inherit the trait from an affected parent equally) rules out sex - linked dominant.

Answer:

D. Autosomal dominant