Among the 202 referred infants, 10 (5%) with seven IDS gene variants were diagnosed with confirmed MPS II (Group 1), 151 (75%) with nine IDS gene variants were classified as having suspected MPS II or pseudodeficiency (Group 2), and 41 (20%) with five IDS gene variants were classified as not having MPS II (Group 3) (Table 1). Here, IDS is linked to mucopolysaccharidosis type 2.