The goal of this study is to determine why Eosinophilic Esophagitis (EoE) occurs and attempt to develop new blood tests for this condition. Individuals with known EoE food sensitivities and/or anaphylactic food allergy to milk, egg, wheat, and/or soy are eligible for enrollment as index subjects. IgE and EoE food allergies are to be established by clinical history and/or prior laboratory testing. A related or unrelated control subject will be recruited for each successfully enrolled index subject.

The goal of this study is to evaluate the effectiveness of a new blood test for Eosinophilic Esophagitis (EoE). Eligible participants include patients undergoing their first upper endoscopy for evaluation of EoE, or who have already been diagnosed with EoE, but whose food sensitivities are currently unknown. The findings of this study will contribute to the development of clinical diagnostic tools (ie. blood tests for food allergies) that will decrease the time needed to identify food sensitivities, and subsequently reduce the time to symptom resolution for newly diagnosed patients with EoE.

Healthy control children are needed to help participate in a study on Immunometabolic Dysregulation. The study involves one visit to CHOP to measure the participant's height and weight, learn more about their medical history, and take a blood sample. The goal of this study is to better understand how immune function changes throughout childhood. Our goal is to find which factors may influence the immune system by comparing patients who have problems with their immune system with those who do not. Participating in this study helps CHOP to advance the health and well-being of children in our community with a focus on those with immunometabolic dysregulation. Participants of this study will be compensated for their time and energy.

Food allergies are a major public health issue affecting an estimated 8% of U.S. children, and possibly up to 10% of adults. Thirty-two (32) million patients have food allergies in the US alone and no cure currently exists. This study is a biorepository (large collection) of samples from patients with a physician-diagnosed and/or an oral food challenge-confirmed food allergy. The repository is potentially a rich resource for advancing the field of food allergy. This study aims to collect blood from patients who have had a positive oral food challenge or have been diagnosed as having a food allergy based on a positive skin prick test or elevated levels of allergen specific-IgE antibodies and a convincing history. The biorepository will also include blood from individuals with no history of food allergies.

The purpose of this research study is to understand what happens to the immune systems and gut microbiomes (gut bacteria) of people who have a food allergy while they undergo an oral desensitization protocol. We will also study the immune systems and gut microbiomes of people without food allergy to better understand if the changes we see are due to oral desensitization or to natural development of these systems.

The purpose of this registry is to gather information from people with food allergies. The information collected includes allergic reactions, specific food allergies, and how food allergies affect people's quality of life. Participants are directed to a website, complete a consent form, and then are prompted to answer on-line questionnaires about their food allergies. Participants are compensated for their time.