Hunter Syndrome- 11 Years of Enzyme Replecament Therapy in Estonian Patient

Hunter syndrome (mucopolysaccharidosis II, MPS II) is a rare, X-linked metabolic disease caused by a deficiency of the lysosomal enzyme, iduronate-2-sulfatase (I2S) . The clinical spectrum of Hunter syndrome spans a wide range, from an attenuated to a severe phenotype . Patients usually appear normal at birth, but symptoms typically begin to appear between 2 and 4 years of age. All affected patients experience progressive course of disease including hepatosplenomegaly, skeletal and joint involvement resulting in reduced joint range of motion and contractures, and heart and airway disease. Recombinant human I2S (idursulfase) was approved for the treatment of Hunter syndrome in 2006. Idursulfase is administered intravenously on a weekly (0,5mg/kg). Improvements included reduction in urinary GAG excretion, reduction in liver and spleen volume, and improvements in respiratory function.

Aim: To present clinical and laboratory data of the Estonian MPSII patient, who has been on enzyme replacement treatment (ERT) during 11 years.

Clinical data: Child presented at the age of age 3,5 years with coarse face, hepatomegaly (+ 3 cm from costal margin). Gradually developed joint stiffness, restricted movements and hearing loss. ERT was started at the age of 10 years with the weekly infusion 0,5 mg/kg.

Results: Following 11 years of ERT at the age of 21 years patient has short stature (-2 SD), minimal hepatomegaly and no cardiomegaly. Urinary GAG excretion is within reference range and disease has shown no significant progression. Detailed data are presented.

Conclusion: Idursulfase has modified significantly the the natural course of MPS II in patient. As effective disease modifing treatment is available for MPS II early identification of patients is crucial to improve final outcome of patients.