Dr. William A. Gahl graduated from the Massachusetts Institute of Technology and earned his M.D. and Ph.D. from the University of Wisconsin. He served as pediatric resident and chief resident at the University of Wisconsin hospitals and completed clinical genetics and clinical biochemical genetics fellowships at the NIH. Dr. Gahl elucidated the basic defects in cystinosis and Salla disease and helped bring cysteamine to new drug approval by the Food and Drug Administration as the treatment for cystinosis. He has published over 650 papers, reviews, book chapters, and editorials, trained 42 biochemical geneticists In 2008, he established the NIH Undiagnosed Diseases Program (UDP), which has made more than 350 rare disease diagnoses and discovered 30 new genetic diseases. Dr. Gahl expanded the UDP to a national Undiagnosed Diseases Network and a worldwide Undiagnosed Diseases Network International. He established American Board of Medical Specialties certification for medical biochemical genetics. Dr. Gahl received the Dr. Nathan Davis Award for Outstanding Government Service from the AMA, the Service to America Medal in Science and the Environment, the EURORDIS Lifetime Achievement Award, and numerous other awards. In 2019, he was elected to the National Academy of Medicine.