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Non-STR DNA Markers: SNPs, Y-STRs, LCN and mtDNA

Interpretation Guidelines

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Due to the difficulties described on the previous pages, if a laboratory implements LCN (Low Copy Number) DNA analysisspecial interpretation guidelines must be developed. While these may differ in detail between laboratories, a number of general principles can be enumerated:17

  • Every allele in the evidence sample that is reported should be replicated by duplicate or triplicate analysis
  • Heterozygous peak ratios are not a robust measure of allelic association
  • Negative controls that contain alleles consistent with the evidence profile require that the evidence samples be reanalyzed. Negative controls with alleles present that do not correspond with alleles in the evidence samples may be ignored, with caution.
  • Allele dropout in the evidence sample has to be considered a possibility at those loci exhibiting an apparent homozygous profile.
  • If there is a single allele in the evidence profile that does not match the potential donor's profile, then allelic drop-in should be considered.

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