Prediction of qualitative outcome of oligonucleotide microarray hybridization by measurement of RNA integrity using the 2100 Bioanalyzer™ capillary electrophoresis system

RNA quality is critical to achieve valid results in microarray experiments and to save resources. The RNA integrity number (RIN) can be measured with minimal sample consumption by microfluidics-based capillary electrophoresis. To determine whether RIN can predict the qualitative outcome of microarray hybridization, we measured RIN in total RNA samples from 484 different experiments by the 2100 Bioanalyzer system and correlated with the percentage of present calls (%pc) of downstream oligonucleotide microarrays. The correlation coefficient for RNA and %pc in all 408 samples for which the bioanalyzer algorithm was able to produce an RIN was 0.475 (p < 0.05), ranging from 0.039 to 0.673 for different tissue- and assay-type subgroups. Multivariate analysis found RIN to be the best predictor of microarray quality as assessed by %pc, outperforming the 28S to 18S ratio. For a %pc threshold of 25% and 35%, we determined optimal cut points for RIN at 7.15 and 8.05, respectively. Using the suggested cut points, RIN can support the final decision whether a certain RNA sample is appropriate for successful microarray hybridization.