Inclusion Criteria:  - All EGIDs patients aged 0-18 years and followed at the centers involved in the study will be considered eligible. Informed consent must be obtained from each enrolled patient and signed by a parent/legal guardian and patient (when older than six years).  Exclusion Criteria:  - This study will not include patients with:  a diagnosis of EGIDs made more than five years before the study participation; a diagnosis of EoE not in line with current international guidelines; a secondary cause of intestinal eosinophilic inflammation (inflammatory bowel diseases, autoimmune diseases, vasculitis, graft versus host disease, malignancies).