Michigan Food and Atopic Dermatitis (M-FAD) Program - Molecular Analytics Project

Food allergy-only group Inclusion Criteria: * Have a known history of food anaphylaxis to peanut, tree nut, egg, milk, or sesame confirmed by an allergist. * Have had skin and blood food allergy testing to the food allergen in question within the past 6 months. Meet the 80% likelihood positive predictive value threshold for allergy based on at least 1 of either the skin or blood immunoglobulin E (IgE) tests per current literature corrected for age. See protocol for more details. * No history of atopic dermatitis Food allergy plus atopic dermatitis group Inclusion Criteria: \- Meet the "food allergy only group" inclusion criteria except this group must also have atopic dermatitis. Atopic dermatitis without food allergy Inclusion Criteria: * Have a present diagnosis of atopic dermatitis by an allergist and/or dermatologist. * Have no history of food allergy, past or present. Control Group Inclusion Criteria: \- No history of food allergy or atopic dermatitis, past or present. Exclusion Criteria for all groups: * People younger than age 10 or older than age 55 * Any active cardiovascular disease, cancer, pulmonary disease except well-controlled asthma, or other condition that would preclude an OFC otherwise. Mild conditions that would not preclude an OFC are allowed (i.e., controlled hypertension or a surgically removed skin cancer that is resolved would not be exclusionary for this study, for example). * Any medication use that cannot be stopped temporarily for the OFC that would interfere with the OFC result. Medications in this category include antihistamines (first or second generation) within 1 week. * Any skin condition aside from atopic dermatitis per inclusion criteria groups that might impact the study, including such conditions as autoimmune skin conditions (such as psoriasis), congenital ichthyoses, hyper-IgE syndromes. * Any recent change (within 6 months) of starting or stopping a biologic medication, such as dupilumab, tezepelumab, or others that might interfere with atopic dermatitis or food allergy. * Any past or present history of oral immunotherapy (OIT) for any food allergen. * Pregnancy - females of childbearing age will be asked and self-report pregnancy status.