DNA Sequencing · Pathology

What is the purpose of incorporating unique molecular identifiers (UMIs) into NGS libraries?

  1. To increase the overall read length during sequencing
  2. To distinguish true variants from PCR artifacts
  3. To multiplex more samples per flow cell
  4. To fragment the DNA at defined restriction sites
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Correct answer: To distinguish true variants from PCR artifacts

UMIs are short, random nucleotide sequences ligated to each DNA fragment before PCR amplification. By grouping reads derived from the same original fragment, UMIs allow bioinformatic tools to collapse PCR duplicates and identify consensus sequences, effectively removing PCR-induced errors and improving the detection of low-frequency variants.

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