sjTREC quantification using SYBR quantitative PCR for age estimation of bloodstains in a Japanese population.

Individual age is a phenotypic trait that provides useful information in forensic investigations. Levels of signal joint T-cell receptor rearrangement excision circle (sjTREC) in human peripheral blood are known to decline with increasing age. The advantages of sjTREC quantification are the simple procedures and highly accurate age estimation results. Whereas TaqMan quantification PCR (qPCR) is widely used for sjTREC quantification, SYBR qPCR assay is not routinely used for evaluating ethnic data. Therefore, we focused on the advantages of the SYBR qPCR assay, which is cheaper and simpler to set up than the TaqMan probe assay. In this study, we developed a SYBR qPCR assay for sjTREC quantification from bloodstains from a Japanese population and evaluated the strength of correlation between sjTREC levels and actual age. The results were obtained from 194 individuals ranging from 18 to 81 years old, and showed a negative correlation between sjTREC level and individual age (r =  -0.786). The equation for age estimation was Age =  -6.27 dCt (CtTBP - CtsjTREC) - 25.841 with standard error ±8.0 years. Furthermore, this formula for the SYBR assay can be applied to not only fresh bloodstains, but also whole blood and bloodstains up to 1 month old. These results indicate that SYBR qPCR is an effective method for age estimation from bloodstains, and its practicality and affordability make it an attractive sjTREC quantification technique.

Polymorphisms in the canine IL7R 3'UTR are associated with thymic output in Labrador retriever dogs and influence post-transcriptional regulation by microRNA 185.

Interleukin-7 (IL-7) and its receptor (IL-7R) are essential for T cell development in the thymus, and changes in the IL-7/IL-7R pathway have been implicated in age-associated thymic involution which results in a reduction of naïve T cell output. The aim of this study was to investigate the relationship between IL7 and IL7R genetic variation and thymic output in dogs. No single nucleotide polymorphisms (SNPs) were identified in the canine IL7 gene, but a number were present in the canine IL7R gene. Polymorphisms in the IL7R exon 8 and 3'UTR were found to be associated with signal joint T cell receptor excision circle (sj-TREC) values (a biomarker of thymic output) in young and geriatric Labrador retrievers. Additionally, one of the SNPs in the IL7R 3'UTR (SNP 14 c.1371 + 446 A > C) was found to cause a change in the seed-binding site for microRNA 185 which, a luciferase reporter assay demonstrated, caused changes in post-transcriptional regulation, and therefore might be capable of influencing IL-7R expression. The research findings suggest a genetic link between IL7R genotype and thymic output in dogs, which might impact on immune function as these animals age and provide further evidence of the involvement of IL-7/IL-7R pathway in age-associated thymic involution.

Forensic Application of Age Estimation Using Signal Joint T-Cell Receptor Excision Circles in Human Lymphoid Tissues / 대한법의학회지

The declining tendency of signal joint T-cell receptor excision circles (sjTRECs) in peripheral blood is known to be age-dependent, and their quantification in blood or bloodstains has recently been introduced as a tool for age estimation. Lymphoid tissues such as the thymus and spleen represent potential candidates for age estimation because they undergo age-related structural and functional changes. In the present study, the correlation between age and sjTREC levels in human lymphoid tissues, namely the thymus, spleen, and blood, obtained from autopsy cases were investigated, with the goal of establishing a reliable age estimation model. Results showed negative regression curves with coefficient values of r=-0.410, r=-0.611, and r=-0.584 for thymus, spleen, and blood, respectively. In addition, this model was testing using thymus samples from the torsos of dismembered bodies from two real forensic cases, and results showed the predicted ages to be close to the actual ages of the victims. Further study will be required to improve accuracy and reduce estimation error, particularly within the lower age range. Nonetheless, these results suggest that quantification of sjTRECs in not only blood but also in other lymphoid tissues could be a useful tool for age estimation in forensic cases.