Patient description: A 34 year old man comes to the clinic complaining of dizziness and severe diarrhea since yesterday. He has returned from an international trip few days ago and was living in a camp in Sudan for a month. He developed abdominal pain followed by bloating and nausea as well as loose bowel movements. Soon he was having profuse watery diarrhea without odor. The stool is watery and white but the patient has no fever. Blood pressure is 95/62 lying down and drops to 75/40 standing. The skin turgor has reduced. HR is 110 and he looks ill with dry mucosa. V. cholerae was seen in dark-field microscopy of a fresh stool specimen. The lab study is as bellow: Sodium 137 meq/L Potassium 2 meq/L Chloride 94meq/L CO2 15 meq/L Fecal leukocytes None seen Fecal occult blood Negative

Clinical trial eligibility criteria: eligible ages (years): 0.0-99.0,  Food Allergy Loeys-Dietz Syndrome Atopic Dermatitis Eosinophilic Esophagitis All participants must meet the following 1. Be 2 to 99 years-old at the time of enrollment for participants who will be seen at the NIH CC; be 0 (newborn) to 99 years-old at the time of enrollment for participants who will submit mail-in samples or participate in telehealth visits. Only viable neonates will be enrolled. 2. Willing to allow storage of blood, buccal swabs, saliva, nasal swabs, stool samples, and other clinically appropriate tissue specimens for future use in medical research 3. Required to have a primary care or other physician who will manage all health conditions related or unrelated to the study objectives FOR In addition to the general listed above, affected participants must meet 1 of the following 1. Have a clinical history of an immediate hypersensitivity reaction to food(s) and be sensitized to food allergen(s) (as evidenced by positive SPT or allergen-specific IgE testing) 2. Be sensitized (as evidenced by positive SPT or allergen-specific IgE testing) to food allergen(s) but have no overt clinical history of IgE-mediated symptoms when they eat that food(s) 3. Have a suspected genetic or congenital disorder potentially associated with food allergy or related condition, as determined by the principal investigator (PI) or associate investigators (AIs) 4. Have a diagnosis of eosinophilic esophagitis (EoE), or clinical suspicion for EoE as determined by the principal investigator (PI) or associate investigators (AIs) 5. Have a history of atopic dermatitis based on self-report or physician assessment. FOR In addition to the general listed above, unaffected relatives must meet the following 1. Be a relative of an affected participant 2. Be unaffected by food allergy (as determined by clinical history and/or allergy testing) or be unaffected by the genetic condition under study FOR In addition to the general listed above , healthy volunteers must meet the following 1. Be unrelated to an affected participant 2. Be unaffected by food allergy (as determined by clinical history and/or allergy testing) or be unaffected by the genetic condition under study The following additional apply for participants undergoing leukapheresis: 1. Age greater than or equal to 12 years for affected participants; age greater than or equal to 18 years for unaffected relatives and healthy volunteers 2. Stable hematologic paramaters (definition: white blood cell count > 2,500/ L, hemoglobin > 10 g/dL, and platelet count > 75,000/microliter)  Participants will be excluded for any of the following Presence of conditions that, in the judgment of the investigator or the referring physician, may put the participant at undue risk or make them unsuitable for participation in the study Inability to participate for the duration of the study The PI deems that participation in the study would not be expected to advance the study goals Additional apply for participants who are undergoing endoscopsy with biopsies strictly for research purposes. Participants will be excluded from participating in this procedure if they meet any of the following 1. uncontrolled asthma or Grade 3 or higher by the American Society of Anesthesiologist s.Physical Status Classification System (http://www.asahq.org/resources/clinicalinformation/.asa-physical-status-classificatio n-system) 2. history of adverse reaction to conscious sedation or general anesthesia required for endoscopy 3. hemoglobin < 12 g/dL 4. platelet count < 100,000 microL 5. PT INR >1.3 or PTT prolonged by > 3 seconds 6. pregnant or breastfeeding 7. viral screens positive for HIV or hepatitis B or C 8. severe unstable myocardial ischemia or cardiomyopathy 9. severe hypoxemia due to chronic pulmonary disease 10. recent abdominal surgery 11. anticoagulant therapy that cannot be interrupted Additionally, unaffected relatives and healthy volunteers will be excluded from endoscopy if they meet any of the following 1. history of reflux or use of acid-suppression medication (including over-the-counter medication) within the last 6 months 2. chronic GI or immunologic disease 3. clinically indicated EGD or colonoscopy within the past 12 months 4. use of systemic corticosteroids within the past 6 months 5. have a history of EGID including EoE 6. younger than 18 years of age