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Quality assurance of RNA-Seq workflows with spike-ins controls
Drozd, Tomáš ; Turk, Andreas (oponent) ; Mehnen, Lars (vedoucí práce)
Spike-in controls such as External RNA Controls Consortium (ERCC) or Lexogen‘s Spike-In RNA Variants (SIRVs) have become essential when it comes assessment of technical variability. Since the E0 SIRVs have identical concentration, variations in their estimated concentration can be used to infer the technical variability from single replicates. This is more economic than the standard approach, which estimates the technical variance from multiple replicates. The DESeq model, a standard tool for differential expression, was modified based on spike-ins information to estimate technical variability. Subsequently, the probability of a change in expression due to technical variability was obtained. A high variation between SIRV transcript read counts was discovered, giving rise to another approach based on estimation of variability for each trasncript separately. This innovative approach revealed better performance on datasets, where only technical variability was present for cross-condition analysis for a given number of replicates per condition. It was observed that increase in number of samples results in higher reliability for estimation. However, spike-ins, especially SIRVs, improved performance of analysis than estimation based on endogenous genes when a few replicates are available. Further reasearch is needed for normalizing technical varibility to estimate significant changes in biological variation.
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