1. From Johns Hopkins University, Baltimore, MD (JEH-F, KJS, JM, and HB); the McKusick-Nathans Institute of Genetic Medicine, Greenberg Center for Skeletal Dysplasias, Baltimore, MD (JEH-F and HB); the Bloomberg School of Public Health, Baltimore, MD (KJS and JM); and AI DuPont Hospital for Children, Wilmington, Delaware (CIS)