Structural and bioinformatics analysis of the L238Q suggest that this mutation causes a significant reduction in the IDUA enzyme's potential catalytic activity, and this mutation may be more severe than other mutations contributing to the Hurler-Scheie syndrome phenotype, presumably causing the psychiatric disease.
The missense mutation L238Q, when paired with a nonsense mutation, is associated with significant, late-onset brain disease: psychiatric disorder, cognitive deficit, and general decline starting at a later age than in Hurler syndrome with a mutation-related rate of GAG accumulation and its pathologic sequelae.