A preliminary assessment of the ForenSeq™ FGx System: next generation sequencing of an STR and SNP multiplex

The ForenSeq™ FGx System (Illumina, San Diego, CA) was initially evaluated in concordance with SWGDAM guidelines for internal validation to determine the quality of the system's components: the ForenSeq™ DNA Signature Prep Kit reagents, the MiSeq FGx™ instrument, and the ForenSeq™ Universal Analysis Software, for the analysis of targeted, forensically informative single nucleotide polymorphisms (SNPs) and short tandem repeats (STRs). This multiplex consisted of STRs (autosomal, X, and Y) and SNPs (identity, ancestry, and phenotypic) that were run using one preparation process. Overall, the ForenSeq™ FGx System performed as well as the traditional capillary electrophoresis-based method in producing usable profile information, along with additional information that could aid in investigative leads. The MiSeq FGx™ System was validated using DNA samples in studies testing reproducibility, repeatability, concordance, sensitivity, and mock case single donor samples. Overall, genotyping results for STRs and SNPs were concordant with the profiles generated from conventional STR analysis using Identifiler and SNPs typed by 23andMe analysis. Genotypes of the ForenSeq™ aSNPs were used to evaluate biogeographical ancestry estimations using ForenSeq™ Universal Analysis Software, FROG-kb database (KIDD aiSNP 55 panel), and 23andMe. The system was shown to provide reproducible genotypes and reliable results were obtained at levels as low as 50 pg. All mock case samples were concordant with the donor profile. The results support consideration of the ForenSeq™ FGx System as an acceptable alternative to current STR and SNP analysis, pending formal developmental and internal validation studies.