One GWAS study identifies 3 susceptibility loci related to the epithelial barrier function in ulcerative colitis patients: HNF4A regulating the expression of cell junctions; CDH1 encoding E-cadherin, a main component of adherent junctions; and LAMB1 encoding laminin beta 1 subunit, expressed in the intestinal basement membrane [48]. This evidence concerns the gene LAMB1 and ulcerative colitis.