An 18-month-old boy with coarse facial features, corneal clouding, skeletal dysplasia (dysostosis multiplex), hepatosplenomegaly, and recurrent respiratory infections is suspected to have a lysosomal storage disorder. Enzyme assay confirms alpha-L-iduronidase deficiency. This child most likely has:

• A Hurler syndrome (MPS IH) — IDUA deficiency, most severe MPS I phenotype ✓
• B Hunter syndrome (MPS II) — iduronate-2-sulfatase deficiency, X-linked
• C Sanfilippo syndrome (MPS III) — heparan sulfate accumulation
• D Morquio syndrome (MPS IV) — galactose-6-sulfatase deficiency

Explanation

Alpha-L-iduronidase deficiency causes MPS I, and the most severe end of the spectrum is Hurler syndrome (MPS IH). It presents in early infancy with coarse features, dysostosis multiplex, corneal clouding, organomegaly, and intellectual disability, with death usually in first decade. Hunter syndrome (MPS II) is differentiated by X-linked inheritance, absence of corneal clouding, and iduronate-2-sulfatase deficiency. Morquio has normal intelligence and no corneal clouding. HSCT is the treatment for Hurler if done before age 2.5 years.

Reference: Ghai Essential Pediatrics, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.