Serum proteins AXIN1, TNFSF14, RNASE3, EN-RAGE, OSM, ST1A1, CA13 and NADK were identified as markers with the most promising specificity/sensitivity and predictivity between healthy and disease groups, while IL-17A and TNFRSF9 enabled differentiation between IBD and IBS patients. This evidence concerns the gene NADK and inflammatory bowel disease.