't Hoen, P.A.C. et al. Nat. Biotechnol. doi:10.1038/nbt.2702 (15 September 2013).

Large-scale RNA sequencing, or RNA-seq, is widely used to profile gene expression in cell and tissue samples. The Genetic European Variation in Health and Disease (GEUVADIS) medical sequencing consortium recently investigated the reproducibility of the results of this popular technique. Members of the consortium in seven sequencing centers sequenced the mRNA and small RNA from lymphoblastoid cell lines derived from 465 individuals, and they analyzed the sources of technical error. They identified some biases due to insert size and GC content, provided a set of quality measures for any RNA-seq project, and proposed suggestions on how to overcome technical biases. The news is good: technical variation in RNA-seq is small, and cross-laboratory comparisons are possible when standardized protocols are followed.