Influencing Factors on Postmortem Protein Degradation for PMI Estimation: A Systematic Review

Abstract

The present review provides an overview of the current research status on the effects of influencing factors on postmortem protein degradation used to estimate the PMI (postmortem interval). Focus was set on characteristics of internal and external influencing factors and the respective susceptibility and/or robustness of protein degradation. A systematic literature search up to December 2020 was conducted on the effect of influencing factors investigated in the context of postmortem protein degradation in the tissues of animals and humans using the scientific databases PubMed and Google Scholar, as well as the reference lists of eligible articles. We identified ten studies investigating a total of seven different influencing factors in degrading tissues/organs (n = 7) of humans and animals using six different methodological approaches. Although comparison of study outcomes was impeded by the high variety of investigated factors, and by high risk of bias appraisals, it was evident that the majority of the influencing factors concerned affected protein degradation, thus being able to modulate the precision of protein degradation-based PMI estimation. The results clearly highlight the need for a thorough screening for corresponding factors to enable the introduction of appropriate correction factors and exclusion criteria. This seems especially relevant for the protein degradation-based study of human PMI to increase the reliability and precision of the method and to facilitate a broader applicability in routine forensic casework.

Keywords: age; body weight; degradation; influencing factor; insects; postmortem interval; protein; sex; temperature; time since death.

Figure 1

Flow chart of the systematic literature search according to PRISMA guidelines.

Figure 2

Frequency diagrams of analyzed influencing factors, species, tissues and methods.

Figure 3

Risk of bias assessment of included studies. Green, low risk of bias; yellow, moderate risk of bias; red, high risk of bias.

Figure 4

Effects of influencing factors [12,14,18,19,20,21,22,23,24,25].