A study in humans identified the mir-3126-5p as a pro-fibrotic microRNA present in exosomes from the pericardial fluid of atrial fibrillation patients, where it was reported to drive cardiac fibrosis [Silva et al. DOI:10.3390/ijms25158329]. In a separate forensic investigation in humans, the mir-3126-5p was found to be differentially expressed and shared across three pairs of monozygotic twins, indicating its potential as a biomarker for distinguishing genetically identical individuals [Xiao et al. DOI:10.1016/j.fsigen.2019.05.003].