A study in humans demonstrated that the expression profile of the piR-hsa-21126 provided valuable information for discriminating forensically relevant biological fluids [Wang et al. DOI:10.1016/j.fsigen.2019.07.015]. A study in humans identified the piR-hsa-21126 as a piRNA positively correlated with aging in blood samples stored for eight years, with Pearson correlation coefficients of r = 0.706 in massively parallel sequencing and r = 0.239 in RT-PCR validation [Fang et al. DOI:10.1007/s00414-023-03028-8].