Mendelian inheritance · USMLE Step 1

A mitochondrial disorder is suspected in a family. Which of the following inheritance patterns is expected?

  1. Affected fathers transmit disease to daughters only
  2. Affected mothers transmit disease to all children
  3. Affected mothers transmit disease to sons only
  4. Affected fathers transmit disease to all children
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Correct answer: Affected mothers transmit disease to all children

Mitochondrial DNA is inherited exclusively from the mother. Therefore, all children of an affected mother can inherit the condition. Fathers cannot transmit mitochondrial disorders.

Difficulty: Medium Question 5 of 20

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