The problems of clinical trials and registries in rare diseases.

Clinical trials to evaluate patients affected by rare diseases are often hampered by the difficulty of recruiting a critical sample size. Registries for rare conditions are thus extremely powerful tools for overcoming recruitment problems. Here we present and discuss the international experience with alpha1-antitrypsin deficiency achieved by the Alpha One International Registry, and national experience obtained with a large series of patients with pulmonary alveolar proteinosis. Copyright (c) 2010 Elsevier Ltd. All rights reserved.