International Journal of Legal Medicine最新文献

Genetic factors are known to have important roles in sudden unexplained death (SUD) of apparently healthy individuals. Currently, molecular autopsy is considered an effective diagnostic tool in the multidisciplinary management of SUD. Recent studies highlighted the contribution of regulatory variants to complex genetic disorders. Pathogenic variants within the untranslated regions of SUD susceptibility genes were also identified in certain cases. However, the functional validation of pathogenic variants outside of the coding regions remains challenging. As the most direct method, transcriptome analysis could be performed at the same time with molecular autopsy to identify the abnormal expression of SUD susceptibility genes, while the post-mortem degradation of mRNA in myocardial tissues has made it difficult to interpret the transcriptome profiling results. In this study, we performed a retrospective analysis-based prioritization of SUD susceptibility genes based on the distribution of pathogenic genetic variants in previous studies with molecular autopsy findings reported. After gene prioritization, we analyzed the transcriptome data of 432 left ventricle tissues with different sampling time intervals from the Genotype-Tissue Expression database, in order to characterize the degradation pattern of prioritized SUD susceptibility genes. Furthermore, RNA degradation difference between unfrozen and thawed samples was investigated. We demonstrated that with proper segmentation of genes according to their degradation patterns, a partial least squares-discriminant analysis could effectively recognize the expression difference of targeted genes between normal samples and simulated SUD cases. Taken together, our findings presented a strategy for the interpretation of RNA profiling results during the forensic investigation of SUD.

Diagnosis of death due to electrocution is difficult when typical electric marks are absent. A valid diagnostic method based on useful biomarkers are needed for these atypical electrocution cases. Herein we utilized formalin-fixed paraffin-embedded samples that are archived in our forensic center to conduct label-free proteome analysis in the aim of screening differentially expressed proteins (DEPs) for diagnosis of atypical electrocution. By using cases dying from mechanical injury and drug intoxication as negative controls, a total of 1591 proteins were identified, among which 128 proteins (8.0%) were DEPs to the atypical electrocution cases. These DEPs were mainly enriched in processes involved in cellular metabolism, DNA replication and gene transcription. The vast majority of the DEPs (121/128, 94.5%) were downregulated, while the remaining DEPs were upregulated in the hearts from atypical electrocution. Mitofusin-2 (MFN2) and Nucleolin (NCL) were the top upregulated and downregulated DEPs, respectively, that showed the greatest fold-changes. Immunohistochemical staining in independent case series verified that both MFN2 and NCL altered significantly in heart specimens from atypical electrocution death. Cardiac expression of MFN2 and NCL were not affected by decedents' age, sex, or postmortem interval. Receiver operating characteristic (ROC) curve analysis revealed that the areas under the curve (AUC) of the two proteins were 0.8925 and 0.9008, with diagnostic sensitivity being 87.54% and 88.89%, and specificity being 74.19% and 84.12%, respectively. Our results suggest that cardiac MFN2 and NCL are potential useful biomarkers for forensic diagnosis of atypical electrocution death.

Objectives: Age estimation plays a major role in the identification of unknown dead bodies, including skeletal remains. We present a novel age estimation method developed by applying a deep-learning network to the coxal bone and lumbar vertebrae on post-mortem computed tomography (PMCT) images.

Materials and methods: The coxal bone and lumbar vertebrae were targeted in this study. Volume-rendered images of these bones from 1,229 individuals were captured and input to a convolutional neural network based on the visual geometry group 16 network. A transfer learning strategy was employed. The predictive capabilities of age estimation models were assessed by a 10-fold cross-validation procedure, with mean absolute error (MAE) and correlation coefficients between chronological and estimated ages calculated for validation. In addition, gradient-weighted class activation mapping (Grad-CAM) was conducted to visualize the regions of interest in learning.

Results and conclusion: The estimation models created showed low MAE (range, 7.27-6.44 years) and high correlation coefficients (range, 0.84-0.91) in the validation. Aging-induced shape changes were grossly observed at the vertebral body, coxal bone surface, and other sites. The Grad-CAM results identified these as regions of interest in learning. The present method has the potential to become an age estimation tool that is routinely applied in the examination of unknown dead bodies, including skeletal remains.

Vertebral artery injuries (VAIs) are rarely observed in forensic practice and can result from either penetrating injuries or blunt force trauma to the neck. The identification of such injuries represents a pivotal challenge for forensic pathologists, due to the protected anatomical course of these vessels, particularly in their extracranial tract. Over the years, several approaches have been proposed to address this issue, including vessel gross examination through different dissection techniques, the water injection method and, more recently, post-mortem computed tomography angiography (PMCTA), which is currently deemed the gold standard approach. However, no studies have employed contrast-enhanced radiological techniques using an ex-situ approach to investigate VAIs.The aim of this study is to investigate the diagnostic potential of fluoroscopy and contrast-enhanced micro-CT in detecting extracranial vertebral artery lesions via an ex-situ approach. Cervical blocks (C1-C3) from three forensic cases of neck stab wounds were collected, and fluoroscopy and contrast-enhanced micro-CT, using Barium Sulfate and Diatrizoate Sodium as contrast agents respectively, were performed. The above radiological techniques proved accurate and reliable in identifying vascular injuries, exhibiting enhanced diagnostic performance compared to conventional macroscopic examination. Fluoroscopy provides dynamic imaging, enabling real-time detection of contrast leakages, while contrast-enhanced micro-CT allows simultaneous assessment of both vascular injuries and bone fractures. Therefore, these promising techniques could serve as complementary tools to conventional diagnostic approaches, offering an accurate and comprehensive characterization of the cervical injury pattern in cases of fatal penetrating neck trauma.

In forensic casework, unraveling the criminal nature of an event requires not only identifying the individual source of specific biological stains but also confirming their cellular origin. Recent studies have demonstrated the feasibility of identifying body fluids using specific mRNA markers and linking body fluids to their donors via coding region SNPs (cSNPs) within these mRNAs. Nanopore sequencing enables the detection of more cSNPs within longer mRNA amplicons due to its long-read capability. In this proof-of-principle study, we developed a targeted mRNA nanopore sequencing panel to simultaneously infer body fluid sources and identify individuals. This panel includes 12 body fluid-specific mRNAs and two reference genes (RGs), with a total of 41 cSNPs included in these 14 mRNA transcripts. Sequencing data showed that specific mRNAs were highly expressed in peripheral blood, semen, and menstrual blood, with an average read proportion exceeding 95% (excluding RGs reads). Cross-reactivity was observed in saliva and vaginal secretions, but all body fluid samples could still be accurately clustered. Alternative alleles were detected for 16 cSNPs, and genotyping results for randomly selected samples were validated for consistency with Sanger sequencing. The system demonstrated discriminatory power (DP) ranging from 0.5645 to 0.9017, providing information about the body fluid donor. However, further research is needed to identify more specific mRNAs, introduce additional highly polymorphic cSNPs, and perform evaluations on larger populations.

[Abstract] Short tandem repeat (STR) loci within the human genome are extensively utilized in forensic DNA analysis because of their high level of polymorphism. At present, the combined DNA index system (CODIS) STRs are the principal ones adopted in the majority of general-purpose forensic kits. Moreover, non-CODIS STRs can serve as valuable supplementary tools for resolving complex paternity cases, conducting evolutionary studies, and performing population genetics analyses. Along with non-CODIS STRs, unusual DNA profiles have been consistently identified, as observed with CODIS STRs. In this present study, we investigated the allelic distribution and population genetics parameters of the D21S2055 locus in a cohort of 258 unrelated individuals from Fujian Province, China. The locus exhibited significant genetic diversity, with twenty-one distinct alleles, mostly spanning a size range from 16.1 to 38. Notably, a large off-ladder allele, 57.2, which was also included in the findings. The core repeat sequence of this allele was found to be [CTAT]₂CTAA[CTAT]₁₃[TATC]₃TAT[TATC]₁₄. TACTATCTCTATAT[TATC]₃TAT[TATC]₁₄[TATC]₂. The population genetic parameters, including the power of discrimination (PD), probability of paternity exclusion (PE) and polymorphic information content (PIC), were calculated as 0.9687, 0.7388, and 0.8576, respectively. In conclusion, it is essential to conduct population genetic analysis before applying non-CODIS STRs in forensic applications. Special emphasis should be placed on large off-ladder alleles that may extend beyond the designated locus region or overlap with an adjacent locus.

Kinship verification using biometric traits is crucial for finding missing children, rapid forensic identification, and social media analysis. Ear biometrics is gaining attention due to its uniqueness, permanence, and non-intrusiveness. However, current research on ear-based kinship verification is limited, and the factors associated with ear similarities across kinship-related individuals require to be evaluated. To fill this gap, our study developed deep learning models to quantify the similarity between ear images and conduct the kinship verification task. Two ear image datasets, namely SCED and CNKE, were collected from Chinese subjects. The SimiNet model, which utilized a pre-trained ResNet50 as its backbone, was constructed to evaluate the cosine similarity between ear image pairs. For kinship verification, the VTrans model was established by combining a pre-trained VGG16 with Transformer modules. Based on the cosine similarity, the SimiNet model obtained 93.53% accuracy and an AUC (Area Under the Curve) of 0.98 for personal verification. The similarity analysis further revealed that kinship-related individuals of the same sex displayed higher ear similarity scores. The VTrans model attained 71.17% accuracy and an AUC of 0.76 on the CNKE dataset. Heatmaps revealed that the VTrans model focused on the helix and the upper half of the ear during kinship verification. The model code has been provided in Github ( https://anonymous.4open.science/r/SimNet_VTrans-EB41 ) to facilitate refinement in future research. Our study has successfully established deep learning models for ear similarity quantification and kinship verification, providing effective tools for biometric forensic identification.

Paternity testing is a well-established application of forensic genetics, generally providing accurate results based on inheritance laws. However, in rare cases, genetic anomalies may arise, complicating the interpretation of DNA profiles and requiring careful evaluation. In this study, we describe a paternity case involving a rare tri-allelic pattern observed at the CSF1PO locus. To confirm the anomaly, genetic material from multiple family members was analysed using different kits. The pattern was consistently verified across all amplification attempts, demonstrating its reliability and its concordance with a specific individual. This case emphasises the importance of careful interpretation in genetic testing and considers the potential implications of such anomalies for DNA analysis. Furthermore, it calls for collaboration among forensic disciplines and experts to address similar findings in forensic and medical genetics.

Carrion decomposition is an important component of the ecosystem and plays a significant ecological role in the food chain. During decomposition, arthropods and microorganisms help to decompose and recycle organic matter and nutrients. Although research has been conducted on microorganisms and arthropods associated with carrion across different biogeoclimatic ecoregions, no study has identified these communities from carrion placed under a tropical rainforest. Therefore, this study aims to investigate the arthropod, bacterial, and fungal communities associated with Sus scrofa Linnaeus. carrion placed in a tropical rainforest in Malaysia. Adult flies and maggots and other arthropods were collected during the forensic entomological survey. The specimens collected were killed, separated, preserved in 70% ethanol, and identified using a stereomicroscope in the laboratory. Swab samples were collected from the skin, anal, and oral cavity of the wild boar carrion. Both bacterial and fungal communities were identified using Sanger sequencing. Data on temperature and humidity were recorded with a data logger throughout the four-day experiment. The results demonstrated that the most isolated bacteria were those of uncultured_bacteria, Ignatzschineria sp. and Gram-negative bacteria, especially Acinetobacter sp., during the early stages of decomposition. Furthermore, the consistent presence of Ascomycota fungi, particularly Exophiala sp., Yarrowia sp., and Meyerozyma sp., suggests their unique occurrence specifically in the tropical rainforest. A total of 219 adult flies and about 9,200 larvae were collected from a wild boar carcass over three days, with Chrysomya pinguis and Chrysomya villeneuvi being the main species, and the latter displaying notable predatory behaviour. These results present for the first time the dominant arthropods, bacteria and fungi inhabiting the carrion in one of the oldest rainforests in the world. (Keyword: Carrion, decomposition, bacteria, fungi, arthropods, tropical rainforest, Malaysia).