TY - JOUR
T1 - Performance of a method for weighting a range in the number of contributors in probabilistic genotyping
AU - McGovern, Catherine
AU - Cheng, Kevin
AU - Kelly, Hannah
AU - Ciecko, Anne
AU - Taylor, Duncan
AU - Buckleton, John S.
AU - Bright, Jo Anne
PY - 2020/9
Y1 - 2020/9
N2 - Uncertainty in the assignment of the number of contributors (NoC) can be encountered, particularly in higher-order mixtures, where alleles may be shared between contributors, may have dropped out, or may be masked by the stutter artefacts or allelic peaks of a more dominant contributor. Most probabilistic genotyping software requires the assignment of NoC prior to interpretation. NoC has been described as a nuisance parameter. Taylor et al. [1] describe a method to weigh the probability of the profile under different values of N and incorporate this into a likelihood ratio (LR). Within this paper we explore the performance of this variable number of contributors (varNoC) method programmed within the probabilistic genotyping software STRmix™. The desired combination of performance and runtime was obtained using the default STRmix™ version 2.7 MCMC settings in conjunction with a 2.5 % hyper-rectangle range, at least 10,000 naïve MC iterations and 8 MCMC chains. The varNoC LR demonstrated the typical sensitivity and specificity behaviour seen in previous studies, with a high level of reproducibility given repeat analyses. Profiles previously demonstrating ambiguity in the NoC assigned using conventional estimation methods, were able to be reliably interpreted and a varNoC LR assigned.
AB - Uncertainty in the assignment of the number of contributors (NoC) can be encountered, particularly in higher-order mixtures, where alleles may be shared between contributors, may have dropped out, or may be masked by the stutter artefacts or allelic peaks of a more dominant contributor. Most probabilistic genotyping software requires the assignment of NoC prior to interpretation. NoC has been described as a nuisance parameter. Taylor et al. [1] describe a method to weigh the probability of the profile under different values of N and incorporate this into a likelihood ratio (LR). Within this paper we explore the performance of this variable number of contributors (varNoC) method programmed within the probabilistic genotyping software STRmix™. The desired combination of performance and runtime was obtained using the default STRmix™ version 2.7 MCMC settings in conjunction with a 2.5 % hyper-rectangle range, at least 10,000 naïve MC iterations and 8 MCMC chains. The varNoC LR demonstrated the typical sensitivity and specificity behaviour seen in previous studies, with a high level of reproducibility given repeat analyses. Profiles previously demonstrating ambiguity in the NoC assigned using conventional estimation methods, were able to be reliably interpreted and a varNoC LR assigned.
KW - Forensic DNA
KW - Number of contributors
KW - Probabilistic genotyping
KW - STRmix
UR - http://www.scopus.com/inward/record.url?scp=85088152355&partnerID=8YFLogxK
U2 - 10.1016/j.fsigen.2020.102352
DO - 10.1016/j.fsigen.2020.102352
M3 - Article
AN - SCOPUS:85088152355
VL - 48
JO - Forensic Science International: Genetics
JF - Forensic Science International: Genetics
SN - 1872-4973
M1 - 102352
ER -