Pedigree analysis · USMLE Step 1

Which scenario describes pseudodominance that might mislead a pedigree analyst?

An autosomal dominant trait that skips an entire generation
A recessive trait recurring across generations via inbreeding
An X-linked dominant trait expressed only in affected females
A mitochondrial trait transmitted only through affected males

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Correct answer: A recessive trait recurring across generations via inbreeding

Pseudodominance is when a recessive trait mimics dominant inheritance — for example, appearing in successive generations in consanguineous families or where the allele is common — which can mislead a pedigree analyst.

Difficulty: Medium Question 11 of 19

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