Natural History of Severe Allergic Inflammation and Reactions

Background: \- Allergic inflammation is central to allergy-related diseases and disorders, such as asthma, food allergies, and atopic dermatitis. Atopic dermatitis, commonly called eczema is a chronic, noncontagious skin condition, usually starting in the first years of life, which causes itching and scaling of an individual s skin. Because atopic dermatitis is a common condition in children who have allergy-related diseases, including asthma, researchers are interested in studying both individuals with atopic dermatitis and their close relatives (parents and children) to better understand how allergy-related diseases develop and progress. In addition, some patients with inherited disorders with features including atopic dermatitis or other aspects of allergy such as food allergy, asthma, hay fever, hives, and others, will also be seen. Objectives: \- To study the natural history of diseases of allergic inflammation, such as atopic dermatitis or genetic disorders associated with allergic inflammation. Eligibility: * Children and adolescents between 1 month and 21 years of age who have a documented history of moderate to severe atopic dermatitis. * Individuals between 1 month and 80 years of age who have a suspected genetic or inherited allergy disorder related to atopic dermatitis or allergic pathways. * Child and adult relatives of eligible participants will also be studied on this protocol. Design: * The study will require one initial visit to the National Institutes of Health Clinical Center (lasting 1-5 days), as well as any required follow-up visits for treatment and research studies. Participants will receive treatment for atopic dermatitis and other allergic diseases as part of the study for up to 1 year. * Participants will have some or all of the following tests as part of this study: * A detailed physical examination and medical history * Allergy skin prick testing to examine participants' responses to different allergens. * Blood samples for additi