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1

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

David A. Russell , Erin M. Gorden , Michelle A. Peck , Christina M. Neal , Mary C. Heaton , Jessica Bouchet ,
a
a
a,*
a
a
a
Alexander F. Koeppel , Elayna Ciuzio , Stephen D. Turner , Carmen R. Reedy a
a
a
a
Affiliations:
a Signature Science, LLC, Charlottesville, VA, USA
*Corresponding author at: Signature Science, LLC, Charlottesville, VA, USA.
Email address: drussell@signaturescience.com

Abstract
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.

Introduction

DNA profiling with short tandem repeats (STRs) continues to be the workhorse and gold
standard in DNA forensics. STRs have been vetted through the court system and are widely
accepted for DNA identification, 1,2 providing high discriminatory value for source
attribution/identification. However, due to the high mutation rate of STRs, kinship analysis is
limited to close familial matches. Additionally, traditional STR profiles are uploaded to CODIS,
a forensic database comprised of STR profiles from forensic evidence and known
perpetrators, limiting the generation of new investigative leads to only those that hit to
previously investigated crimes.

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