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Highly Parallel Analysis of Complex Genetic Mixtures

NCJ Number
Date Published
July 2018
8 pages
The findings and methodology are presented for a project whose major goal was the development of a highly parallel DNA sequencing method for improving the analysis of genetic mixtures.

Many forensic evidence samples are composed of DNA mixtures from different individuals; however, for many evidence samples obtained in a criminal investigation, it is difficult, if not impossible, for current forensic methods to identify each person who contributed to the sample. The current research project developed a new sequencing technology called STR-Seq. Based on a next-generation sequencing (NGS) approach, this technology enables the parallel analysis of thousands of microsatellites, also known as sequence tandem repeats (STRs), for any given sample. This method has numerous advantages compared to the current standard used in most forensic work, which involves using a molecular amplification process known as PCR, which is analyzed with a system called capillary electrophoresis (CE). STR-Seq does not use this older technology. Instead, it involves a specialized technology for DNA sequencing of forensic samples. As a result of multiple improvements, STR-Seq delineates multi-component complex DNA mixtures at low fractional representations. The project used the STR- Seq technology in conducting a large population study of approximately 1,000 individuals. It characterized 1,915 new microsatellites loci that included the discovery of a new class of STRs that are highly polymorphic. It also developed a new method of measuring specific STR genotypes that are represented in a mixture; and it improved on the sequencing of low DNA quantities. 4 figures, 9 references, and a listing of scholarly products from the research project

Date Published: July 1, 2018