Characterisation and Filtering of Systemic Noise in Next Generation Sequencing of Short Tandem Repeats with Applications in Forensics

In forensic analysis of DNA samples, short tandem repeat (STR) regions in the genome are selectively amplified with PCR to subsequently determine which alleles are present. The DNA polymerase used to amplify STRs with PCR is known to ‘slip’ occasionally, which results in an additional PCR product having one repeat unit more or less than the original allele. These so-called ‘stutter products’ may coincide with other alleles present in the sample and may therefore overshadow very small components of mixed DNA samples. In this project, methods are developed to characterise the appearance of stutter products and other systemic noise in NGS data, to filter this noise in forensic DNA samples, and thereby to identify the true alleles in these samples, increasing the sensitivity of forensic DNA analysis for samples with very small contributions.