Carolyn R. Steffen, David L. Duewer, Margaret C. Kline, John M. Butler
Concordance evaluations are important to conduct to determine if there are any allelic dropout or null alleles present in a data set. These studies are based on the fact that there are a variety of commercial short tandem repeat (STR) multiplex kits available to the forensic community that have different configurations of STR markers. The placement of the markers can vary between kits because the primer sequences have been designed to amplify different polymerase chain reaction (PCR) product sizes. When multiple primer sets are utilized, there is a concern that allele dropout may occur due to primer binding site mutations that impact one set of primers but not another. These null alleles become evident only when data sets are compared. Multiple concordance studies have been performed at NIST with a standard sample set using various STR multiplex kits including Identifiler, MiniFiler, PowerPlex (PP) 16, PP ESX 17, PP ESI 17, and in-house assays. Various discordant results have been identified using concordance software developed at NIST and confirmed by DNA sequencing.
profiles in DNA
concordance, DNA typing, multiplex PCR, null allele, primer sequences, short tandem repeat, STR kits