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

SNPs in Forensic Genetics

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Theoretically, the advantages of a SNP-based (Single Nucleotide Polymorphism) system include:

  • Potential for automation
  • Ability to analyze degraded DNA (with a number average molecular weight equivalent to the sum of the lengths of the two primers)
  • Direct interrogation of genes whose variants have predictive consequences for a phenotypic trait

Disadvantages include:

  • Difficulties with body fluid mixture detection and analysis
  • Requirement for large numbers of individual SNPs
  • Uncertainties about the availability and robustness of appropriate multiplex-capable analytical platforms 

It is not likely that SNP typing will replace STRs (Short Tandem Repeats) as the principal method for human identification, but there are specialized instances in which this typing is warranted. 

SNPs were the basis of the variation of the ABO and isoenzyme classic genetic markers used prior to the DNA revolution in forensic biology; the pre-DNA detection technology was based upon antigens and proteins.

Read more about ABO and enzymes in course: Laboratory Orientation and Testing of Body Fluids and Tissues for Forensic Analysts.

The first generation of PCR-based (Polymerase Chain Reaction) forensic kits employed the HLA DQAlpha1 and PM systems, which comprised a series of SNP markers detected by allele specific oligonucleotide hybridization using a reverse dot blot format.

Read more about HLA DQAlpha1 and PM systems in course: Crime Scene and DNA Basics for Forensic Analysts.

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