A comparison of the effects of PCR inhibition in quantitative PCR and forensic STR analysis.

In this paper we compare the effects of three representative PCR inhibitors using quantitative PCR (qPCR) and multiplex STR amplification in order to determine the effect of inhibitor concentration on allele dropout and to develop better ways to interpret forensic DNA data. We have used humic acid, collagen and calcium phosphate at different concentrations to evaluate the profiles of alleles inhibited in these amplifications. These data were correlated with previously obtained results from quantitative PCR including melt curve effects, efficiency changes and cycle threshold (Ct) values.

A study of PCR inhibition mechanisms using real time PCR.

In this project, real time polymerase chain reaction (PCR) was utilized to study the mechanism of PCR inhibition through examination of the effect of amplicon length, melting temperature, and sequence. Specifically designed primers with three different amplicon lengths and three different melting temperatures were used to target a single homozygous allele in the HUMTH01 locus. The effect on amplification efficiency for each primer pair was determined by adding different concentrations of various PCR inhibitors to the reaction mixture.

Developmental validation of reduced-size STR Miniplex primer sets.

This paper describes a developmental validation study of three Miniplex sets covering 12 of the 13 CODIS loci. As these new sets will be used for the analysis of degraded and low level DNA, the validation studies were performed using 100-125 pg of DNA, the lowest input level at which peak balance, peak intensity, and allele consistency were stable. To demonstrate the applicability of the Miniplex sets to forensic casework, these validation studies were completed in accordance with the Scientific Working Group on DNA Analysis Methods (SWGDAM).

The application of miniplex primer sets in the analysis of degraded DNA from human skeletal remains.

A new set of multiplexed PCR primers has been applied to the analysis of human skeletal remains to determine their efficacy in analyzing degraded DNA. These primer sets, known as Miniplexes, produce shorter amplicons (50-280 base pairs (bp)) than standard short tandem repeat (STR) kits, but still utilize the 13 CODIS STR loci, providing results that are searchable on national DNA databases. In this study, a set of 31 different human remains were exposed to a variety of environmental conditions, extracted, and amplified with commercial and Miniplex DNA typing kits.

A study on the effects of degradation and template concentration on the amplification efficiency of the STR Miniplex primer sets.

In forensic DNA analysis, the samples recovered from the crime scene are often highly degraded leading to poor PCR amplification of the larger sized STR loci. To avoid this problem, we have developed STR markers with redesigned primer sequences called "Miniplexes" to produce smaller amplicons. To assess the effectiveness of these kits, we have tested these primer sets with enzymatically degraded DNA and compared the amplifications to a commercial kit.