Expression of microRNAs in human platelet-poor plasma: analysis of the factors affecting their expression and association with proximal genetic variants

To translate circulating microRNAs (miRNAs) into the clinic, a deeper understanding of the factors affecting their expression is needed. In this study, we explored the features affecting the expression of miRNAs and their genetic regulation using the expression data of 103 miRNAs obtained by qPCR in the platelet-poor plasma of 104 subjects. The principal components (PCs) of the expression of the miRNAs were associated with technical and biological features (e.g., synthetic controls or sex) and with blood cell counts. Also, the associations with proximal genetics variants were analysed. We found that haemolysis marker (dCt hsa-miR-23a-3p-hsa-miR-451a) was correlated strongly (β = 0.84, p = 2.07x10−29) with the second PC, which explained 10.1% of the overall variability. Thus, we identified haemolysis as a source of variability for miRNA expression even in mild hemolyzed samples (haemolysis marker dCt