Non-self DNA on the neck: a 24 hours time-course study

Abstract

Non-self DNA is normally present on skin due to DNA transfer occurring during daily activities. The understanding of persistence and accumulation of foreign DNA on the neck can assist in the interpretation of DNA evidence collected from an assaulted victim. Establishing the composition and level of non-self DNA present is relevant, especially in cases where the victim cohabits with other individuals, such as partner and children. This study investigated the persistence and accumulation of non-self DNA on the neck, over the course of 24 h. DNA samples were collected from the neck of 20 adult volunteers at three time-points, on two days. The detection of a partner's DNA and DNA from unknown sources was studied in relation to the living arrangement and to the activities performed by each individual. An increased number of non-self alleles were detected over time. Partner's DNA was observed to accumulate during the day and to persist when an individual was absent from the shared home environment. DNA from unknown contributors was found on the neck of individuals that used public transport, attended public spaces and had social interactions. The data acquired from this study will help to increase knowledge on the composition of DNA present on an individual's neck in a daily situation.

Recent advances in forensic biology and forensic DNA typing: INTERPOL review 2019–2022

“…Other recent studies on DNA-TPPR include examining prevalence and persistence of DNA or saliva from car drivers and passengers [ [310] , [311] , [312] ], evaluation of DNA from regularly-used knives after a brief use by someone else [ 313 ], studying the accumulation of endogenous and exogenous DNA on hands [ 314 ] and non-self-DNA on the neck [ 315 ], considering the potential of DNA transfer via work gloves [ 316 , 317 ] or during lock picking [ 318 ], and investigating whether DNA can be recovered from illicit drug capsules [ 319 , 320 ] or packaging [ 321 ] to identify those individuals preparing or handling the drugs.…”

Limitations of qPCR to estimate DNA quantity: An RFU method to facilitate inter-laboratory comparisons for activity level, and general applicability

“…The data-set also includes background DNA samples. The second dataset (B) consisted of 118 samples collected from the necks of simulated victim assaults, described in detail by Fantinato et al [4]: epithelial cells were recovered, that were generally low template and degraded. The results from the two data sets are plotted in fig 2 along with their regressions.…”

“…The notion of using average peak height of a DNA profile as a proxy measurement for DNA quantity was introduced by Tvedebrink et al [1, 2], along with a method to apportion quantities per contributor based on analysis of contributor-specific alleles. The method was improved by [3, 4, 5] who used probabilistic genotyping, EuroForMix [6], to determine the relative proportions of known and unknown contributors ( M x ), that constitute a mixture. The output was used to calculate likelihood ratios given activity level propositions based upon .…”

Limitations of qPCR to estimate DNA quantity: An RFU method to facilitate inter-laboratory comparisons for activity level, and general applicability

“…The notion of using average peak height of a DNA profile as a proxy measurement for DNA quantity was introduced by Tvedebrink et al [1, 2], along with a method to apportion quantities per contributor based on analysis of contributor-specific alleles. The method was improved by [3, 4, 5] who used probabilistic genotyping, EuroForMix [6], to determine the relative proportions of known and unknown contributors ( M x ), that constitute a mixture. The output was used to calculate likelihood ratios given activity level propositions based upon .…”