HMOX1 and cystic fibrosis: Using the mean DNA methylation in the region, we found that HMOX1 was differentially methylated in NEC samples (Student p = 0.018) and blood cell samples (Wilcoxon p = 0.009) of CF patients compared with controls, but the direction of the methylation change was not the same in the two tissue models (Fig. 4a, b).