Monogenic IBD was identified in 17 patients (36.2%), with diagnoses including Familial Mediterranean Fever (FMF) (n = 9), glycogen storage disease type 1b (n = 2), XIAP deficiency (n = 1), CDG (n = 1), DOCK8 deficiency (n = 1), IL10 receptor alpha defect (n = 1), LRBA deficiency (n = 1), and NFKB2 deficiency (n = 1). This evidence concerns the gene XIAP and hyperinsulinemic hypoglycemia, familial, 4.