Population-Based Newborn Screening for Mucopolysaccharidosis Type II in Illinois: The First Year Experience

Objectives To assess the outcome of population-based newborn screening for mucopolysaccharidosis type II (MPS II) during the first year of screening in Illinois. Study design Tandem mass spectrometry was used to measure iduronate-2-sulfatase (I2S) activity in dried blood spot specimens obtained from 162 000 infant samples sent to the Newborn Screening Laboratory of the Illinois Department of Public Health in Chicago. Results One case of MPS II and 14 infants with pseudodeficiency for I2S were identified. Conclusions Newborn screening for MPS II by measurement of I2S enzyme activity was successfully integrated into the statewide newborn screening program in Illinois.