Allergy and Immunology Natural History Study

This is a long-term natural history study — meaning it follows patients over time without providing experimental treatment. It is studying people who have or may have inherited disorders involving allergies, mast cells (cells involved in allergic reactions), or immune regulation problems. **You may be eligible if...** - You are any age (from birth to 99) - You are known or suspected to have an inherited condition affecting allergic inflammation, mast cells, or immune function - You are a blood relative of someone already enrolled in the study - You are willing to have blood stored for future immune research **You may NOT be eligible if...** - You have an acquired immune problem (such as from chemotherapy or cancer) that the investigator believes would interfere with the study - You or your guardian are unable or unwilling to give informed consent Talk to your doctor to see if this trial is right for you.