We analyzed 22 potential serum biomarkers at baseline, during the manifestation of SkAE, and after the healing of SkAE in serum of 7 IBD patients (Supplementary Figure S4). We found that a marker closely associated with epithelial integrity, L-FABP, was lowered during the manifestation of SkAE (Figure 4A). Conversely, I-FABP increased significantly after SkAE were healed (Figure 4A). The gene discussed is FABP2; the disease is inflammatory bowel disease.