In diseased conditions, many genes and gene products are visible in the bloodstream. So my question is whether we can find traces of microRNA which is involved in disease and disorder in blood serum?
In my opinion this is possible. Maybe packed in vesicles (e.g. see Han EC, Choi SY, Lee Y, Park JW, Hong SH, Lee HJ. FASEB J. 2019 Dec;33(12):13412-13422. doi: 10.1096/fj.201901575R. Epub 2019 Sep 21. ).