Of note, substantially greater levels of NR5A2 (FC = 7.85; MW p < 0.0001), FOXA2 (FC = 141.62; MW p < 0.0001), GATA6 (FC = 262.06; MW p < 0.0001) and SMAD6 (FC = 11.27; MW p < 0.001) transcripts were validated in BO biopsies (n = 17 samples and 3 technical replicates) relative to normal oesophagus (n = 17 samples and 3 technical replicates) in follow-up real time RT-PCR validation studies with significance determined by non-parametric (Mann-whitney) testing appropriate for gene expression data (Fig. 2B). Here, SMAD6 is linked to bronchiolitis obliterans syndrome.