IDS and mucopolysaccharidosis type 2: For the infants with MPS II, nine carried hemizygous variants, i.e., c.254C>T, c.817C>T, c.1025A>G, c.311A>T, c.1400C>T, c.1007-1666_c.1180+2113delinsTT, and IDS inversion, which caused deficiency of IDS enzyme activities, ranging from 0.20 to 0.83 μmol/g protein/4h.