Genetic Testing and Counseling · USMLE Step 1

Which family member should ideally be the first one tested (proband) when performing genetic testing in a family with suspected inherited disease?

  1. A healthy sibling
  2. An affected individual
  3. A parent only
  4. All family members simultaneously
Show answer and explanation

Correct answer: An affected individual

Testing an affected individual first helps identify the causative variant; once identified, targeted testing (cascade testing) can be offered to at-risk relatives — minimizing uncertain or inconclusive findings.

Difficulty: Medium Question 15 of 20

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