Subjects eligible for enrollment in this study include children and adults with food allergy and patients with a known/suspected genetic or congenital disorder potentially associated with these phenotypes. Unaffected relatives (children and adults) of an enrolled subject and healthy volunteers (children and adults) will also be eligible for enrollment as controls. Most participants will be followed for 2 years, although participants with an identified genetic or congenital disorder and a subset of participants with food allergy may be followed until this study ends (up to 12 years).