Pedigree analysis · USMLE Step 1

Which inheritance pattern would you suspect if multiple siblings are affected but neither parent shows the trait and there is consanguinity?

  1. Autosomal dominant with reduced penetrance
  2. Autosomal recessive
  3. X-linked dominant
  4. Y-linked
Show answer and explanation

Correct answer: Autosomal recessive

Consanguinity raises the chance that both parents carry the same recessive allele, so affected children can appear from unaffected parents — a hallmark of autosomal recessive inheritance.

Difficulty: Medium Question 9 of 19

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