Early-onset inflammatory bowel disease (IBD) has a distinct phenotype and should be considered as a specific entity. IBD of very early onset includes ulcerative colitis, Crohn’s disease, and a relatively high proportion of indeterminate colitis. Overall, the disease manifestations are primarily colonic, with severe perianal disease, and severe extra-gastrointestinal manifestations. Early-onset IBD presents with very severe manifestation and guarded prognosis with life-threatening signs and symptoms and needs an aggressive therapeutic approach. Early-onset IBD is unique in its association to metabolic diseases, neutrophil defects, and immunodeficiency states, chronic granulomatous disease, neutropenia, cyclic neutropenia, Wiskott-Aldrich syndrome, leukocyte adhesion defect, hypogammaglobulinemia, common variable immunodeficiency, and other immunodeficiency states. Early-onset IBD can be associated with Hermansky-Pudlak syndrome, glycogen storage disease type 1B, primary defects in tryptophan handling, and familial Mediterranean fever. It is controversial whether the ensuing Intestinal inflammation in metabolic disorders, neutrophil defects and immunodeficeincy states are a form of Crohn’s disease and ulcerative colitis, or a presentation of the primary disease. The very early-onset IBD presents a unique opportunity to study the impact of immunological status, neutrophil role, phagocytic function, gut microflora, metabolic pathways, and environmental factors on the genetic predisposition and the natural history of IBD.
