NADK and irritable bowel syndrome: After removing associations that did not survive HEIDI test and multiple testing correction, genetically predicted higher levels of 3 circulating proteins including MST1 (macrophage-stimulating protein), NADK (Nicotinamide adenine dinucleotide kinase), HGFAC (Hepatocyte growth factor activator) were significantly associated with a decreased risk of IBD (Fig. 2 and Supplementary Table S2).