Clinical and laboratory predictors of monogenic very early onset inflammatory bowel disease

Background: Inflammatory bowel disease (IBD) is a chronic inflammatory disease of the gastrointestinal tract. Treatment for patients who have a monogenic cause of their IBD, often the youngest children, known as very early onset IBD (VEO-IBD), can be different from standard treatment for polygenic cases. Yet, ascertainment of these patients is difficult. Methods: We analyzed cases of VEO-IBD to understand the breadth of monogenic etiology and to identify clinical, laboratory, and flow cytometric correlates of this subpopulation. Results: Genetic causes of very early onset inflammatory bowel disease are highly diverse ranging from pure epithelial defects to classic T cell defects. Flow cytometry, other than testing for chronic granulomatous disease, has a low sensitivity for monogenic etiologies. Poor growth was a clinical feature associated with monogenic causality. Conclusions: Genetic testing is, at this moment, the most robust method for the identification of monogenic cases of very early onset IBD.