In SAM enteropathy and in Crohn's disease there was increased expression of DUOX2, DUOXA2, lipocalin 2, CEACAM 5 and 7, MUC1, SAA 1, 2 and 4, and CXCL5 genes (Supplementary Figs. S2–5, S7 and S10), and these transcripts were further over-expressed in HIV infection (Supplementary Table S2). Here, DUOXA2 is linked to Crohn disease.