Systematic assessment of next-generation sequencing for quantitative small RNA profiling: human plasma pool

Small RNA-seq is increasingly being used for profiling of small RNAs. Quantitative characteristics of long RNA-seq have been extensively described, but small RNA-seq involves fundamentally different methods for library preparation, with distinct protocols and technical variations that have not been fully and systematically studied. Using common sets of reference samples, we evaluated the accuracy, reproducibility and bias of small RNA-seq library preparation for five distinct protocols and across nine different laboratories. As part of this larger study, we assessed reproducibility and diversity of sequencing of mature miRNAs, generating libraries from RNA extracted from human plasma that was pooled from 11 healthy individuals. We find that protocol-specific biases are largely recapitulated in the biological samples, and that inter-protocol bias correction factors estimated from the more comprehensive equimolar synthetic pools can be applied to the biological samples to get more comparable, and in some cases, more accurate estimates of miRNA abundance. A common pool of human plasma RNA was sequenced by 6 different labs, using 1 common library construction protocol (TruSeq), and at least one additional protocol of their choice. A total of 15 sample libraries was produced, each in quadruplicate.