Date of Award
Master of Science (MS)
Dr. Ranjit Vijayan
Dr. Mohammad Shahid Nazir
Short Tandem Repeats (STRs) are short nucleotide sequence repeats consisting of 2-8 base pairs (bp), representing approximately 3% of human DNA. Markers of STRs have been widely used as genetic markers in forensic DNA analysis and have proven to be an extremely discriminating method for human identification in forensics. The main objective of this research was to evaluate a six-dye STR multiplex assay (Virifiler™ Plus) composed of 23 autosomal STR loci, one insertion/deletion polymorphic marker on the Y chromosome, Amelogenin and two internal quality control markers (IQCS and IQCL) using biological stains found in different crime scenes. The study investigated the performance of several tests, including: sensitivity, reproducibility, stability, heterozygote balance, precision, mixture study and concordance study. The results showed that the assay was reproducible, sensitive, accurate and robust. Sensitivity testing showed that a full profile could be obtained even with 63 pg of human DNA. Heterozygous allele balance varied between 60-99% for samples with total DNA input ranging from 1 ng-500 pg. It is also suitable for mixture studies which occur when the evidence contains a mixture of DNA coming from several contributors. All alleles of minor contributors were called for ratios of 1:1, 1:3 and 3:1. Overall, the current study demonstrates that this multiplex assay is robust and reliable as an assay for human identification with forensic casework samples, and most importantly is suitable to be used in Dubai Forensic Laboratory and other forensic laboratories worldwide. This study is the first to evaluate Virifiler™ Plus with casework samples.
Al Janaahi, Naeema Saleh, "Forensic Evaluation of 6-Dye Chemistry Kit Composed Of 23 Loi with Casework Samples" (2019). Biology Theses. 20.