The most frequently studied fecal marker was calprotectin (44 studies), with areas under the curves (AUCs) ranging from 0.70 to 0.99 in ulcerative colitis (UC) and from 0.70 to 0.94 in Crohn`s disease (CD), followed by lactoferrin (4 studies), matrix metalloproteinase-9 (3 studies), and lipocalin-2 (3 studies). This evidence concerns the gene LCN2 and ulcerative colitis.