Development of guidelines to designate alleles using an STR multiplex system

We have carried out extensive validation of a multiplex system of 6 STR loci and the Amelogenin sex test to investigate the following characteristics: relative peak areas of heterozygote peaks; non-specific artefacts; stutters caused by slippage of the Taq enzyme; pull-up (an electronic artefact often associated with software). The purpose of this paper is to demonstrate how interpretation guidelines can be formulated by experimentation and analysis using casework samples. Automation allows data relating to band position (in base pairs), peak area and peak height to be easily collected and manipulated in spreadsheets or computer programs. This paves the way to designing expert systems to carry out the interpretative process.