Mendelian inheritance · USMLE Step 1

A father is affected with an autosomal dominant disorder. The mother is unaffected and does not carry the mutation. What is the chance their child will inherit the disorder?

  1. 0%
  2. 25%
  3. 50%
  4. 100%
Show answer and explanation

Correct answer: 50%

Autosomal dominant disorders require only one affected allele. A heterozygous affected parent passes the allele to 50% of children. The remaining children inherit the normal allele.

Difficulty: Medium Question 8 of 20

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