Undiagnosed phenylketonuria can exist everywhere: results from an international survey - Wegberg, Annemiek M. J. van; Trefz, Friedrich K.; Gizewska, Maria; Ahmed, Sibtain; Chabraoui, Layachi; Zaki, Maha S.; Maillot, François; van Spronsen, Francjan J.; Haas, Dorothea; Gramer, Gwendolyn (The journal of pediatrics, 2021)