Molecular diagnostics · USMLE Step 1

Which molecular diagnostic approach would best detect a small insertion or deletion (indel) mutation present at low allele frequency in a mixed cell population?

  1. Sanger sequencing of the locus alone
  2. Next-generation (high-throughput) sequencing
  3. Conventional G-banded karyotyping
  4. Protein gel electrophoresis of the sample
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Correct answer: Next-generation (high-throughput) sequencing

Next-generation sequencing (NGS) can sequence large numbers of DNA fragments in parallel and detect mutations (including indels) even if present at low allele frequency within a heterogeneous cell population, unlike Sanger sequencing which has lower sensitivity in mixed samples.

Difficulty: Medium Question 12 of 21

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