Serum Vitamin D Levels and Markers of Severity of Childhood Asthma in Costa Rica * 1,2,4 John M. Brehm, MD* 1–4 Juan C. Celedón, MD, Dr.PH 5 Manuel E. Soto-Quiros, MD, PhD 5 Lydiana Avila, MD, 1,2,4 Gary M. Hunninghake, MD, MPH, 1,4,6 Erick Forno, MD, 1 Daniel Laskey, BS, 1 Jody S. Sylvia, BS, 7 Bruce W. Hollis, PhD 1,4 Scott T. Weiss, MD 1–4 Augusto A. Litonjua, MD, MPH 1 Channing Laboratory, 2 Division of Pulmonary/Critical Care Medicine, and 3 Center for Genomic Medicine, Department of Medicine, Brigham and Women’s Hospital, Boston, Massachusetts; Department of Medicine, 4 Harvard Medical School, Boston, Massachusetts; 5 Division of Pediatric Pulmonology, Hospital Nacional de Niños, San José, Costa Rica; 6 Division of Pediatric Pulmonology, Children’s Hospital, Boston, Massachusetts; and 7 Darby Children’s Research Institute, Medical University of South Carolina, Charleston, South Carolina. *These authors contributed equally to this manuscript. Address correspondence and requests for reprints to: Juan C. Celedón, MD, Channing Laboratory, 181 Longwood Avenue, Boston, MA 02115 (juan.celedon@channing.harvard.edu ) Funding/Support: This work was supported by grants HL66289, HL089842, HL04370, and T32 HL07427 from the National Institutes of Health. Page 1 of 45 AJRCCM Articles in Press. Published on January 29, 2009 as doi:10.1164/rccm.200808-1361OC Copyright (C) 2009 by the American Thoracic Society.