After RNA had been isolated successfully for 59 samples, RNA quantity was measured using a Nanodrop ND-1000 Spectrophotometer to give the yield and a 260/280 ratio. Agilent Bioanalyser Lab-on-a-chip RNA chips were also run for each sample to check the quality by calculating RNA Integrity Number (RIN) scores. 500 ng of total RNA was labelled using the TotalPrep™ RNA Amplification Kit (Ambion Inc.). For each of the five methods, samples from two visits of an individual were measured on the same Beadchip and samples from each individual were measured on a maximum of three Beadchips to maximise biological reproducibility and minimise technical variability.
