A study in humans identified hsa-let-7d as a potential biomarker, showing it was significantly up-regulated in the peripheral blood mononuclear cells of chronic benzene poisoning patients compared to healthy controls [Bai et al. DOI:10.1016/J.Yexmp.2014.04.011]. In a separate human case-control study, the expression of the let-7d was significantly decreased in venous blood leukocytes from patients with methamphetamine use disorder with psychosis compared to healthy individuals [Sun et al. DOI:10.1016/j.neulet.2019.134725]. A study in mice demonstrated that the let-7d was a member of the Let-7 family identified as predicting high-dose and high-risk radiation exposure and was an important miRNA in a decision tree model for classifying viable versus high-risk subjects at day 1 post-irradiation [Martello et al. DOI:10.1667/RADE-23-00007.1]. In humans, the let-7d was significantly up-regulated in the serum of patients with obstructive sleep apnea syndrome compared to healthy controls and was part of a four-miRNA diagnostic panel with high predictive accuracy [Mo et al. DOI:10.2147/NSS.S382765].