Deficiency of the enzyme leads to the accumulation of these GAGs in tissues throughout the body, playing a central role in the pathogenesis of MPS I. A novel homozygous insertion mutation (c.1172-1173insGCTGCTGGC; G391insLLA) in IDUA was identified in an affected individual in family B. Glycine at position 391 is involved in the formation of torsion angles due to its high degree of rotational ability which maybe lost after the insertion of LLA leading to abnormal function of the enzyme. Here, IDUA is linked to Scheie syndrome.