The purpose of this observational study is to find the best measures to define how well a person with eosinophilic disorder is doing. People with EoE, EoG, EoN and EoC normally undergo endoscopy and/or colonoscopy where cells are collected for microscopic analysis. Treatments are then decided based on how the cells look. We are aiming to compare different tissue components such as inflammatory cell types with clinical symptoms. We want to see if scores on standard questionnaires can give us an idea how well the person is doing.

This is a longitudinal observational study in which individuals (males and females 3 years of age and greater) with EoE, EoG, EoN and EoC will be followed over the course of time to see if standard questionnaires can give us an idea of how well the person is doing.

Participants undergoing standard of care (normal, routine care) endoscopies and/or colonoscopies will have biopsies (small pieces of tissue from the GI tract normally collected during these procedures) collected and used for the research study. Participants will also complete questionnaires related to their symptoms and quality of life. Participants will be followed over the course of time and asked to complete the questionnaires at various time points throughout the study.

Inclusion Criteria:

• Males or females 3 years of age and older
• Mucosal eosinophilia:

EoE ≥ 15 eosinophils/HPF in the distal or proximal esophagus EoG ≥ 30 eosinophils/HPF in 5 HPF's in the body and/or antrum EoN ≥ 53 eosinophils/HPF in the duodenum and/or ≥ 56 eosinophils/HPF in the jejunum and/or ileum EoC ≥ 84 eosinophils/HPF from the transverse or descending colon and/or ≥ 32 eosinophils/HPF from the rectosigmoid colon or a biopsy from any colonic location with ≥ 100 eosinophils/HPF

- Presence of symptoms is required for patients who are newly diagnosed but not required for patients who were previously diagnosed.

Exclusion Criteria:

• History of intestinal surgery other than G tube placement
• Enrolled in a blinded investigational study at the time of the first study visit
• Have esophageal stricture (<3mm)
• Have other identifiable causes for eosinophilia (except Inflammatory Bowel Disease): infections, Gastrointestinal (GI) cancer, other GI inflammatory disease (e.g., Ulcerative Colitis or Crohn's Disease)

Males and females ages 3 or greater with EoE, EoG, EoN or EoC.