This prospective observational study (Predictor and biomarker: leucine-rich alpha-2 glycoprotein for inflammatory bowel disease treatment with adalimumab [PLANET]) aimed to investigate the association of serum LRG levels with disease activity and endoscopic activity in IBD patients treated with adalimumab for 52 weeks, thus examining the usefulness of LRG as a monitoring biomarker during induction and maintenance therapy. This evidence concerns the gene GPHA2 and inflammatory bowel disease.