The Data and Coordinating Center is located at the Cleveland Clinic Foundation. The registry has six major clinical centers: Cleveland Clinic Foundation, Mayo Clinic-Rochester, National Heart, Lung, and Blood Institute, National Jewish Medical and Research Center, New England Medical Center, and Stanford University Medical Center. Data and lung tissue collected by the registry will be used to characterize the clinical features and natural history of the disease and to determine the efficacy of lung transplantation in this disorder. Eligible patients are to be seen yearly for up to 4 years at the Clinical Centers or, in some cases, by individual referring physicians. Tissue collected by the LAM Registry will be stored at a central NHLBI repository. Outcome events include measures of pulmonary function (eg, spirometry and, when available, lung volumes and diffusing capacity), arterial blood gases or oximetry, walking and resting oxygen titration, cardiopulmonary stress testing, cause-specific mortality, functional status, and clinical events associated with lung transplantation.