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Updated: Aug 21, 2026
Enhanced Genetic Analysis of Single Human Bioparticles Recovered by Simplified Micromanipulation from Forensic ‘Touch DNA’ Evidence
Published on: March 9, 2015
Systematic analysis of stutter percentages and allele peak height and peak area ratios at heterozygous STR loci for
Benoît Leclair1, Chantal J Frégeau, Kathy L Bowen
1National DNA Data Bank, Royal Canadian Mounted Police, 1200 Vanier Parkway, Ottawa, Ontario, Canada, KIG 3M8.
Abstract:
To assist the interpretation of STR DNA typing results from forensic casework samples containing mixtures, the range of heterozygous allele peak height and peak area ratios (HR) and stutter percentages (stutter %) for the loci comprised in the AmpFlSTR Profiler Plus (PP) kit were assessed on 468 database and 275 casework single source samples. Stutter % medians were similar for database and casework samples, ranging from 2% to 7%. The upper limit of the stutter value range was 16%, calculated as median +3 SD, although lower locus-specific values could be used. HR medians were 93 +/- 6.5% for database samples, 88 +/- 12% for casework samples. For casework samples, the maximum signal imbalance noted was 52%, calculated as median -3 SD. No significant difference was observed between peak height and peak area calculated values. This study shows the importance of selecting the proper reference database for the establishment of HR threshold values.
