Combined genotyping and biomarker analysis in plasma and/or urine, such as the recently reported plasma heparin cofactor II-thrombin (HCII-T) complex and the urinary dermatan sulfate:chondroitin sulfate (DS:CS) ratio, promises to be a good strategy for determining disease severity in newly diagnosed MPS I patients [2,3,29,30]. This evidence concerns the gene SERPIND1 and Scheie syndrome.