1. Metabolism and Endocrinology Unit (A.O., C.F.), 00161 Rome, Italy
2. Regional Newborn Screening Laboratory of Lombardia Region (C.C.), Children's Hospital V. Buzzi, 20154 Milan, Italy
3. Department of Pediatrics (G.W., M.C.V.), Vita-Salute S. Raffaele University, IRCCS San Raffaele Hospital, 20132 Milan, Italy
4. Department of Cell Biology and Neurosciences, and National Centre for Epidemiology Surveillance and Health Promotion (E.M.), Istituto Superiore di Sanità, 00161 Rome, Italy