Biology subjects

Neal, C. M.

Publications and source records attributed to Neal, C. M..

2 recordsLinked to original sources

bioRxiv2022

Internal Validation of the ForenSeq Kintelligence Kit for Application to Forensic Genetic Genealogy

Forensic Genetic Genealogy (FGG) requires high density single nucleotide polymorphism (SNP) profiles to infer distant relationships. The ForenSeq Kintelligence kit is a recently developed method targeting approximately 10,000 SNPs that were selected to be compatible with genetic genealogy databases, while avoiding medically relevant SNPs. The targeted PCR method is ideal for low input and degraded samples, which are particularly challenging for microarray analysis. We made modifications to library preparation and sample pooling to further enhance the performance of low input samples. To align this FGG method with forensic laboratory standards, we performed an internal validation study in accordance with the Scientific Working Group on DNA Analysis Methods Validation Guidelines for DNA Analysis Methods. The sensitivity and precision and accuracy studies produced accurate and reliable profiles down to 0.05 ng of DNA. The mixture and contamination studies demonstrated that the method could detect the presence of a minor contributor down to 0.02 ng, while system wide contamination was negligible. Nonprobative bone, fired shell casing, and adhesive tape samples performed well with inputs ranging from 0.05 to 1.0 ng of DNA. A bone with a high degradation index and tested at 0.1 ng DNA input resulted in a call rate of 92.9% and a heterozygosity rate of 0.387. We demonstrated the importance of both call rate and heterozygosity rate to assess profile performance. Validating FGG methods is critical to ensuring the reliability and utility of SNP profiles that will be uploaded to genetic genealogy databases for the purpose of generating investigative leads.

genomics↗

bioRxiv2022

Developmental Validation of the Illumina Infinium Assay using the Global Screening Array (GSA) on the iScan System for use in Forensic Laboratories

Microarray processing, which interrogates hundreds of thousands of single nucleotide polymorphisms (SNPs) across the human genome, has recently gained traction in forensics due to its use in forensic genetic genealogy, which is based on analysis using SNPs to compare distant relatives in publicly curated databases for the purposes of developing investigative leads or identifying human remains. To date, there has been no published developmental validation of microarray processing using the Scientific Working Group on DNA Analysis Methods (SWGDAM) Validation Guidelines for DNA Analysis Methods and Federal Bureau of Investigation Quality Assurance Standards. Validation of these methods are warranted to identify samples suitable for microarray analysis and to assess the quality of the data obtained prior to upload to genealogical databases. In this study, we validated the Global Screening Array (GSA) for use in forensic investigations according to SWGDAM guidelines, including the following studies: precision and accuracy, sensitivity, contamination, degradation, species specificity, mock case-type samples, mixtures, repeatability and reproducibility, and stability. Results indicated accurate genotype calls with SNP call rates >95% at DNA input as low as 0.20 ng. In addition to SNP call rate, we developed interpretation thresholds for signal intensity and heterozygosity to allow for sample quality assessment and identification of highly degraded and/or non-human DNA. This study demonstrates that high quality data can be generated from multiple sample types, including mock forensic evidence that simulated the challenges that are often encountered in forensic cold cases.

genomics↗