Advanced Research          

Casework Genetics is looking to revolutionize forensic identification standards. 

Forensic DNA Identification testing, euphemistically referred to as DNA Fingerprinting, is now more than 20 years old.  The current state-of-the-art in forensic laboratory technology, STRs, is over 15 years old.  Since the 1980s the quest has been to define a set of loci that could be reasonably assayed and that exhibited enough polymorphism to make it worth the effort.  That methodology has been exhaustively refined, and is approaching the limits of improvement potential.

Rather than look for new ways to improve STRs, Casework Genetics is looking to revolutionize forensic identification standards.  Our current research focus is on the use of SNP technology to analyze complex mixtures.  Mixtures made in the worst of circumstances with the worst of intensions, leaving the justice field with samples often degraded and disastrous.

Unlike forensics, where SNPs are considered an emerging technology, research in other areas such as pharmacogenomics and Genome Wide Association Studies, to name just two examples, consider SNPs to be a mature technology.  In 2006, bio-medical research operations were routinely using 5,000 SNPs at once, and today, we and others are using more than 1 million loci in a single assay.    It is reasonable to expect that by year’s end, more than 2.5 million SNPs will be an off the shelf product, and 5 million SNPs is on the very near horizon.  The possibilities of statistical analysis in the presence of so much data are nearly overwhelming to consider.

One of the shortcomings with the use of SNPs for human identification is the lack of compatibility with current STR databases.  The number of entries into these databases worldwide is approaching the tens of millions.  The sheer volume of the databases alone makes it inconceivable to consider redoing the input data with SNP loci.  However, because the High Density SNP Arrays provide so much data, it is possible to use SNP allele patterns to infer or identify STR alleles.  This means we could use SNPs genotypes to disclose the STR genotypes of a sample without directly measuring the STR genotype.  Casework Genetics has intellectual property in this area and we are actively pursuing identification of appropriate SNP alleles for these associations.

As the number of SNPs being analyzed increases into the many millions, the ability to resolve the presence of a single genome in more complex mixtures becomes more routine.  Estimates for the level of complexity of mixtures for which a single genotype can be associated  approaches the ability to pick out an  individual from a mixture of thousands.  With arrays containing two and three times more SNP loci, it will be possible to use much more complex mixtures and determine whether an individual has been present at public places such as restaurants, vendors and transportation hubs.  Applications for tracking fugitives, associating individuals with a crime scene locale and understanding the dynamics of criminal groups such as gangs are all amenable to this technology. We are engaged in efforts to bring these innovations to the forensic scientists tool kit.

Genome Wide Association Studies (GWAS) have driven the development of High Density SNP Arrays.  As technology developers like Illumina look further into the needs of the medical research community, they have identified applications that are convergent with the needs of forensic investigators.   One such area relates to  Low Copy Number samples.  Here the driver from the medical field is the desire to analyze the genomes of single cells.  This is highly valuable in determining changes in tumor cells, and will lead to other discoveries about mutation kinetics.  For forensics, Low Copy Number realizes its limit at a single cell.  Casework Genetics is working with Illumina as they develop this exciting technology in order to quickly bring it to the field of human identification.