ABSTRACT
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.