## Clinical Diagnosis This child has **Mucopolysaccharidosis Type II (MPS II, Hunter syndrome)**, confirmed by: - Progressive coarse features and corneal clouding - Hepatosplenomegaly and joint stiffness - Elevated urinary glycosaminoglycans (heparan sulfate, dermatan sulfate) - Iduronate-2-sulfatase deficiency ## Management of MPS II **Key Point:** MPS II is an X-linked lysosomal storage disorder. **Enzyme replacement therapy (ERT)** is the standard of care and the most appropriate next step. ### Enzyme Replacement Therapy (ERT) 1. **Idursulfase (Elaprase)** — recombinant human iduronate-2-sulfatase - Administered intravenously at 0.5 mg/kg weekly - Reduces storage of glycosaminoglycans in tissues - Slows progression of somatic features and improves mobility 2. **Timing of initiation** — should be started as early as possible after diagnosis to prevent irreversible organ damage 3. **Benefits** — improves: - Joint mobility and function - Cardiac function (reduces cardiomyopathy risk) - Respiratory capacity - Hepatosplenomegaly (partial reduction) - **Does NOT cross blood-brain barrier** — does not prevent neurological deterioration in severe forms **High-Yield:** ERT is the **first-line disease-modifying therapy** for MPS II and other mucopolysaccharidoses. It is approved by regulatory agencies and is the standard of care. ### Supportive Care (Concurrent) - Cardiac monitoring (echocardiography annually) - Audiology assessment and hearing aids - Orthopedic management for joint contractures - Respiratory support if needed - Genetic counselling (X-linked; affected males, carrier females) ## Comparison of Management Options | Intervention | Role in MPS II | Evidence | |--------------|----------------|----------| | ERT (idursulfase) | **First-line** | Proven to slow somatic progression; standard of care | | HSCT | Limited role | May benefit CNS in early infantile form; not standard for attenuated form | | Corticosteroids | No role | No evidence; may worsen immunosuppression | | Dietary restriction | No role | Glycosaminoglycans are produced endogenously, not dietary | **Clinical Pearl:** MPS II exists in two phenotypes: - **Attenuated (90%)** — slower progression, normal intelligence, longer survival - **Severe (10%)** — rapid progression, intellectual disability, death by early teens ERT is beneficial in both, but HSCT may be considered in the severe form if performed very early and if a matched donor is available.
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