Systematic study on the analytical parameters relevant to achieve reliable STR profiles, as assessed in a multicentre data set

A set of 16 amplifications following a D-optimal experimental design was planned using the most commonly selected kit and sequencer utilized in a collaborative exercise of the ISFG Italian Working Group GeFI on the molecular characterization of a depurinated DNA sample. The data were evaluated using STRvalidator in order to describe the occurrence of PCR artifacts such as peak imbalance and allele/locus drop outs. The aim of the study was to describe the role of the template amount, number of amplification cycles, volume of the PCR reaction in determining the assay sensitivity and the profiling accuracy as measured by peak heights and areas. The results showed that only by selecting an appropriate ratio of template to PCR reaction solution total volume together with an increase in the number of cycles it could be possible to obtain balanced peaks as well as minimal occurrence of other artifacts. These data are useful to model and understand the PCR artifacts occurrence described in the collaborative exercise.