Pedigree analysis · USMLE Step 1

If two unaffected parents have an affected child, which mode of inheritance is most likely?

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

Correct answer: Autosomal recessive

When two phenotypically unaffected parents produce an affected child, autosomal recessive inheritance is most likely, since both parents can be asymptomatic carriers.

Difficulty: Medium Question 3 of 19

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