Pedigree analysis · USMLE Step 1

In a pedigree, if an affected father transmits the trait to all his daughters but none of his sons, which inheritance pattern is most likely?

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

Correct answer: X-linked dominant

In X-linked dominant inheritance, an affected father passes his X chromosome to all daughters (who are affected) and his Y to sons (who are unaffected), giving exactly this pattern.

Difficulty: Medium Question 8 of 19

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