Midway through the 2010s, the field of DNA analysis experienced a surge of new technologies and new techniques that had the power to revolutionize forensic casework. No matter which technique is used the first few steps of analysis remain the same: DNA extraction, DNA quantification and targeted DNA amplification. Procedural work beyond this point changes depending on analysis technique. While capillary electrophoresis remains the gold standard for DNA analysis, next-generation sequencing, or massively parallel sequencing, is a popular alternative that many forensic labs have begun utilizing.
Capillary electrophoresis (CE) can provide DNA results in just a few hours, and it is simple and inexpensive, with no library sample preparation needed. It can process a majority of sample types to reveal STR (short tandem repeats) allele size. In forensic casework for crimes, this STR data can be run against a national DNA database, like the U.S.’s CODIS (Combined DNA Index System) to match or exclude a suspect.
Next-generation sequencing (NGS) can complete STR and SNP (single nucleotide polymorphism) analysis on one platform. Like CE, next-generation sequencing reveals STR allele size, but it also shows sequence-specific data that adds additional information, such as externally visible characteristics and biogeographic ancestry. Biogeographic ancestry SNPs can help generate investigative leads, even in cold cases with old, highly degraded DNA. Additionally, NGS is compatible with forensic genetic genealogy, a technique that has skyrocketed in popularity since it was used in 2015 to identify the Golden State Killer.
Genetic genealogy relies on SNP or genome sequencing for data that can be used to indicate a person’s relatives. This data can be compared with public databases, such as GEDmatch, as well as private DNA databases in search of an ancestral match. Through matches and extensive genealogical research, a family tree is developed that can help drive an investigation.
Key considerations for purchasing forensic DNA analysis laboratory equipment:
Forensic DNA analysis equipment differs based on desired technique, the number of samples that can be run simultaneously, software and price. If processing casework for law enforcement, equipment and methods need to be validated, which should always be factored into purchasing decisions regarding timelines and budget.
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