STR profiling
Short tandem repeats are highly variable DNA markers widely used for human identification and relationship testing. Traditional forensic workflows commonly separate fluorescently labelled STR fragments by capillary electrophoresis.
Key considerations for STR and NGS forensic analysis
What NGS adds
Next-generation sequencing can determine sequence information within STR alleles rather than relying only on fragment length. It can also multiplex autosomal STRs, Y-STRs, X-STRs, SNPs and other markers depending on the validated panel.
Sequence-level variation
Two alleles with the same length can sometimes contain different internal sequences. Sequence-based STR analysis can therefore increase discrimination in some datasets.
Mixtures and complex samples
Additional sequence information can improve discrimination, but NGS does not automatically solve every mixture. Interpretation still requires validated analytical thresholds, artefact characterization and appropriate statistical methods.
Method validation
A forensic laboratory must validate the exact instrument, chemistry, software and interpretation workflow for its intended use. Results from different platforms require appropriate nomenclature and quality assurance.
Choosing the method
The appropriate technology depends on the forensic question, sample quality, required markers, database compatibility, laboratory validation and reporting framework.
Forensic/legal use note: This material is educational. Evidentiary admissibility, collection authority, consent and procedural requirements are jurisdiction- and case-specific. Follow applicable law, court directions and the requesting authority’s requirements.
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