Corroborating this observation, STAT3 was significantly downregulated in the PBMCs of PTSD patients clearly indicating that the downregulation of AGO2 and DCR1 could be the result of reduced expression of STAT3. We do not know why STAT3 is downregulated in the PTSD PBMCs, but we hypothesize that this in turn causes decreased transcription of both AGO2 and DCR1, which directly diminish the generation of mature miRNAs and the resultant effect is observed as a global downregulation of miRNAs in PTSD PBMCs. This evidence concerns the gene STAT3 and post-traumatic stress disorder.