Monogenic IBD was identified in 36.2% (n = 17) of patients, including nine with Familial Mediterranean Fever and others with glycogen storage disease type 1b (n = 2), XIAP deficiency, chronic granulomatous disease, DOCK8 deficiency, IL10 receptor alpha defect, LRBA deficiency, and NFKB2 deficiency (n = 1 each). This evidence concerns the gene XIAP and hyperinsulinemic hypoglycemia, familial, 4.