The results of the above confirmative methods showed that 2 infants had marked deficiency of IDUA activities were typical of MPS I patients (less than 5% of the reference values, 6.8-37.0 μmol/g protein/hr), and another that showed definitely reduction in IDUA activity might be a carrier (3.5 μmol/g protein/hr). Here, IDUA is linked to Scheie syndrome.