A 2-year-old presents with coarse facies, corneal clouding, hepatosplenomegaly, joint stiffness, and regression of developmental milestones. Urine glycosaminoglycan (GAG) is markedly elevated. Enzyme assay shows absent alpha-L-iduronidase. Which condition is this, and which clinical feature differentiates it from Hunter syndrome (MPS II)?

• A Morquio syndrome (MPS IV); absent corneal clouding and normal intelligence
• B Sanfilippo syndrome (MPS III); severe intellectual disability
• C Maroteaux-Lamy syndrome (MPS VI); normal intelligence
• D Hurler syndrome (MPS IH); corneal clouding distinguishes it from Hunter syndrome ✓

Explanation

Hurler syndrome (MPS type IH) is caused by deficiency of alpha-L-iduronidase leading to accumulation of dermatan and heparan sulfate. The classic triad includes coarse facies, corneal clouding (due to stromal GAG deposition), and hepatosplenomegaly with neurodegeneration. Hunter syndrome (MPS II, X-linked recessive; iduronate-2-sulfatase deficiency) presents similarly but characteristically LACKS corneal clouding — this is the major distinguishing feature between Hurler and Hunter syndromes on clinical examination. Both have coarse facies, hepatosplenomegaly, joint stiffness, and progressive neurodegeneration.

Reference: Ghai Essential Pediatrics, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.