Validation of the PowerPlex 1.1™ Loci for Use in Human Identification

Abstract

STR typing is now the favored method of DNA analysis for the purposes of human identification in the forensic community. The Forensic Services Division of the Detroit Police Department has completed its validation of the PowerPlex 1.1 loci (CSF1PO, TPOX, THO1, vWA, D16S539, D7S820, D13S317, and D5S818) for use in forensic casework. Detroit Metro Area Red Cross samples were typed from each of five racial/ethnic groups--the Hispanic, Caucasian, African American, Asian, and American Indian populations--and allele and genotype frequencies were calculated. A rare off-ladder variant (9.1 allele at D7S820) was identified among the database samples. A number of validation studies were performed. DNA was extracted from different substrates and typed as expected, except for the DNA extracted from leather (signal absent from the D16S539, D7S820, D13S317, CSF1PO, and TPOX loci) and from dirt (no PCR product generated). The minor contributor in the mixture study (250 pg input DNA) was facile to discern. The Concordance study, the variety of fluids from the same individual, and NIST standards studies all produced the expected results. Finally, STR data confirmed previous DNA typing results from adjudicated casework samples.