HLA DQA1 and Polymarker Validations for Forensic Casework: Standard Specimens, Reproducibility, and Mixed Specimens

Abstract

This study describes the testing performed by the Minnesota Forensic Science Laboratory (MFSL) to validate the Amplitype DQA1 and Amplitype Polymarker (PM) PCR Amplification and Typing Kits before implementation for casework. All studies were based on the analysis of mock forensic case samples, which were assembled from various biological samples from individuals at the MFSL. To address the validation of standard specimens, DNA was isolated from semen, vaginal secretions, saliva, urine, and blood samples. Typing results from all tissues from a particular individual yielded the same typing results using both the DQA1 and PM systems. Reproducibility between laboratories was evaluated by having duplicate samples analyzed by a second laboratory. The Roche Biomedical Laboratories (RBL) were sent a duplicate set of mock cases and all analyses including extraction, quantitation, amplification, and typing were performed at the RBL using their established testing procedures. All typing results for both laboratories, from the approximate 30 single source samples analyzed, were in agreement. Mixed specimens were evaluated by examining the results obtained from semen/vaginal, semen/saliva, semen/blood, semen/ urine, and semen/vaginal/blood mixtures. All typing results of these mixtures for both laboratories were in agreement. It was determined that by incorporating a wash step of the sperm cell pellet, a complete separation of the nonsperm cell fraction was more likely to be attained. After completing the above studies, as well as population studies, environmental insult studies, and proficiency testing, the MFSL determined that both kits were suitable for use on forensic casework.