1. Centers for Disease Control and Prevention, Newborn Screening Quality Assurance Program, MS-19, 4770 Buford Hwy., Atlanta, GA 30341-3724
2. NeoGen Screening, Inc., 110 Roessler Rd., Pittsburgh, PA 15220
3. Diagnostic Laboratory for Infectious Diseases and Perinatal Screening, National Institute of Public Health and the Environment, P.O. Box 1, 3720 BA Bilthoven, The Netherlands