This study will establish a registry for participants with eosinophilic esophagitis (EoE) and create a research resource that will provide further insights into EoE.

Eosinophilic esophagitis (EoE) is a newly recognized chronic disease that is increasingly being diagnosed in children and adults. Many patients with EoE also have food allergies. EoE is characterized by inflammation and accumulation of a specific type of immune cell, called an eosinophil, in the esophagus. While there have been several large studies of EoE, very few have focused on the roles the immune system, genetics/heredity, and the environment in EoE.

The samples and information collected from participants will help to identify and understand the genetic mechanisms underlying eosinophilic esophagitis.

The Cincinnati Children's Hospital Medical Center will serve as the Central Laboratory for genetic characterization studies.

Inclusion Criteria:

• Written informed consent/assent from participant and consent from parent/guardian for minors with agreement for genetic testing;
• Documented diagnosis of EoE at any time confirmed by study team (pathology report describing greater than or equal to 15 eosinophils/hpf in peak field of an esophageal biopsy. Participants with eosinophilia in extra-esophageal tissue are permitted).

Exclusion Criteria:

• Participants with known infectious causes of esophageal eosinophilia such as esophageal fungus, gastric H. pylori, or systemic parasites;
• Participants with a history of persistent eosinophilia greater than 1500 cells/mcl of blood.

Participants with biopsy proven Eosinophilic Esophagitis