Several studies have reported higher levels of FCP in IBD patients than in controls, both in adults and in pediatric population [13,14] and, as a laboratory marker, FCP has revealed better diagnostic accuracy than ESR and CRP in differentiating IBD patients from healthy controls and in assessing the disease’s endoscopic and histologic activity [14,15,16,17]. The gene discussed is ESR1; the disease is inflammatory bowel disease.