Characterising the STR locus D6S1043 and examination of its effect on stutter rates

Abstract

The forensic analysis of DNA is most often undertaken by the amplification of short tandem repeats (STR) using the polymerase chain reaction (PCR). DNA amplification can result in production of the target allele amplicon and a by-product called stutter. Stutter is the result of the miscopy of the target allele and is typically one repeat smaller. Stutter is traditionally described as a ratio of stutter and allele height; stutter ratio (SR). The challenge to DNA profile interpretation is most serious whenever stutter products are of a similar height to the minor allelic peaks in a mixed DNA profile. An accurate assignment of peaks and the prediction of their height is important when objectively interpreting forensic DNA profiles. The longest uninterrupted stretch (LUS) of tandem repeats within the allele has previously been shown to be a good predictor of stutter ratio. LUS is determined by sequencing a range of observed alleles at a locus. The locus D6S1043 is a relatively new locus to appear in commercial forensic DNA testing kits. To date however, there has been no comprehensive report of sequencing of this locus. In this work, we sequence a sample of D6S1043 alleles to determine LUS values and investigate allele repeat number and LUS as explanatory variables for SR.

Keywords: D6S1043; Forensic DNA; Interpretation; Sequencing; Stutter.