Intractable diarrhea in infancy and molecular analysis: We are beyond the tip of the iceberg

Background: Intractable diarrhea (ID) could be defined as a syndrome of severe chronic diarrhea associated with malnutrition not easily resolved by conventional management. Aims: To provide an overview on etiology and management of ID patients in Italy in the last 12 years. Methods: The members of Italian Society for Pediatric Gastroenterology, Hepatology and Nutrition (SIGENP) enrolled all ID patients seen between January 1, 2011 and December 31, 2022. Results: 69 children were enrolled (49 M, 20 F; median age at ID onset 9.5 days) from 7 tertiary care pediatric centers. Overall 62 patients had genetic diseases; 3 had infantile Inflammatory Bowel Disease and 1 autoimmune enteropathy in absence of genetic mutations; 2 undefined ID. Defects of intestinal immune-related homeostasis caused ID in 29 patients (42 %). Conclusion: ID is a rare but challenging problem, although the potential for diagnosis has improved over time. In particular, molecular analysis allowed to identity genetic defects in 90 % of patients and to detect new genetic mutations responsible for ID. Due to both the challenging diagnosis and the treatment for many of these diseases, the close relationship between immune system and digestive tract should require a close collaboration between pediatric immunologists and gastroenterologists, to optimize epidemiologic surveillance and management of ID.