A Prospective Natural History Study of Lymphatic Anomalies

Background: The lymphatic system is a network of vessels that carry a clear fluid called lymph through the body. Problems in the lymphatic system can cause pain, fluid buildup, and issues with immunity. There is much researchers do not understand about lymphatic anomalies. In this natural history study, they will collect data from a lot of people over a long time. Objective: To better understand why lymphatic anomalies develop. The goal is to improve future treatments. Eligibility: People aged 0 days and older with a suspected or confirmed lymphatic anomaly. Their unaffected parents or siblings aged 7 years or older are also needed. Design: Participants may remain in the study indefinitely. Affected participants may be evaluated every 10 months to 2 years. Some participants will be seen over telemedicine. Others will be seen at the NIH Clinical Center for 2-5 days. All participants will have a physical exam. They may provide specimens including blood, saliva, hair follicles, stool, skin, and other tissues. Samples may be used for genetic testing. Participants may undergo other tests depending on their medical conditions. The NIH Clinical Center visit may include: Heart tests include placing stickers on the chest to measure electrical activity and using sound waves to capture pictures of the heart. A lung test measures the muscle strength in the chest. Participants will blow into a tube. Photographs may be taken of participants faces and other features. Imaging scans will take pictures of the inside of the body. One scan will measure bone density. One type of scan tracks how lymph fluid moves through the body. Participants will be under anesthesia, and they will be injected with a dye.