Early-Onset Inflammatory Bowel Disease.

The epidemiology of inflammatory bowel disease has changed over the past 4 decades. The incidence is rising dramatically and the age of onset has become younger. This changing landscape of inflammatory bowel disease reflects the new recognition that the youngest children with inflammatory bowel disease are enriched in cases with underlying primary immunodeficiency and monogenic causes. The management of these cases can be quite different, with specific genetic etiologies supporting unique interventions and some requiring hematopoietic cell transplantation for effective treatment.