Other contributions: We thank the CAMP subjects for their ongoing participation in this study. We acknowledge the CAMP investigators and research team, supported by the National Heart, Lung, and Blood Institute, for collection of CAMP Genetic Ancillary Study data. We thank Andy Liu, MD, and Stanley Szefler, MD, (National Jewish; Denver, Colorado); Nadia Hansel, MD, MPH, Greg Diette, MD, MHS, and N. Franklin Adkinson Jr, MD (Johns Hopkins; Baltimore, Maryland); and Karen DeMuth, MD, Robert Strunk, MD, and Mario Castro, MD, MPH (Washington University; St. Louis, Missouri) for their assistance in collection of CD4+ lymphocytes and RNA extraction. We give special thanks to Anne Plunkett, RN, Teresa Concordia, Debbie Bull, LPN, Denise Rodgers, RPFT, and D. Sundstrom, BA, for their assistance with sample collection; Huiqing Yin-DeClue, PhD, Michael McLane, PhD, and Chris Allaire, BSc, for their assistance with T-cell isolations and RNA preparation; and Ankur Patel, BSc, for his assistance with running the microarrays. This work was performed at the Channing Laboratory, Brigham and Women’s Hospital, under appropriate CAMP policies and human subject protections.