Evaluation of parameters in mixed male DNA profiles for the Identifiler® multiplex system
- Authors:
- Published online on: May 12, 2014 https://doi.org/10.3892/ijmm.2014.1779
- Pages: 43-52
-
Copyright: © Hu et al. This is an open access article distributed under the terms of Creative Commons Attribution License [CC BY_NC 3.0].
Metrics: Total
Views: 0 (Spandidos Publications: | PMC Statistics: )
Total PDF Downloads: 0 (Spandidos Publications: | PMC Statistics: )
Abstract
The analysis of complex DNA mixtures is challenging for forensic DNA testing. Accurate and sensitive methods for profiling these samples are urgently required. In this study, we developed 11 groups of mixed male DNA samples (n=297) with scientific validation of D‑value [>95% of D‑values ≤0.1 with average peak height (APH) of the active alleles ≤2,500 rfu]. A strong linear correlation was detected between the peak height (PH) and peak area (PA) in the curve fit using the least squares method (P<2e-16). The Kruskal-Wallis rank-sum test revealed significant differences in the heterozygote balance ratio (Hb) at 16 short tandem repeat (STR) loci (P=0.0063) and 9 mixed gradients (P=0.02257). Locally weighted regression fitting of APH and Hb (inflection point at APH = 1,250 rfu) showed 92.74% of Hb >0.6 with the APH ≥1,250. The variation of Hb distribution in the different STR loci suggested the different forensic efficiencies of these loci. Allelic drop-out (ADO) correlated with the APH and mixed gradient. All ADOs had an APH of <1,000 rfu, and the number of ADO increased when the APH of mixed DNA profiles gradually decreased. These results strongly suggest that calibration parameters should be introduced to correct the deviation in the APH at each STR locus during the analysis of mixed DNA samples.