AB127. Enzyme replacement therapy in patient with mucopolysaccharidosis type II: a case report

Background and objective: Mucopolysaccharidosis (MPS) type II (Hunter syndrome) is an X-linked lysosomal storage disorder due to the deficit of iduronate 2-sulfatase, an enzyme catalysing the degradation of the glycosaminoglycans (GAG) dermatan- and heparan-sulfate. Treatment of the disease is mainly performed by enzyme replacement therapy (ERT) with idursulfase. This article aims to describe clinical characteristics, enzyme activity and genetic finding in the first Vietnamese patient with MPS type II treated with idursulfase (Elaprase) replacement therapy.

Methods: Clinical features, biochemical finding, enzyme activity, mutation analysis and management in a 4 years 6-month-old girl was study. Based on analysis of a patient’s clinical symptoms associated with enzyme iduronate-2-sulphate sulphatase activity measurement in plasma, the diagnosis of MPS type II was therefore made. Genomic DNAs were extracted from peripheral blood leukocytes from the patient and identify mutation of IDS gene, nine exons and their intronic boundaries of the IDS gene were sequenced using genomic DNA from the patient. The patient has been treated with Elaprase infusion every week with the dose of 0.05 mg/kg/week.

Results: A 34-month-old boy was presented with coarse facial at 24 months of age. He was admitted with the features of coarse facial, with frontal bossing, prominent supraorbital ridge, large nose and flat nasal bridge, widely spaced teeth, thickened gingival mucosa, and macroglossia, broadly built of the body habitus with a short neck, broad chest, and protuberant abdomen and Mongolian spots at the back and breech, joint finger stiffness, abdominal distension, palpable liver at 3 cm below the costal margin, sleep disturbances/snoring, mental development delay. Laboratory showed: hepatosplenomegaly in ultrasound with right liver length of 127 mm, spleen length of 93 mm, a 6-minute walk test distance of 240 m, DQ 55%, α iduronate sulphate: 0 nmoL/4 h/mL plasma (normal: 600-1,616), urine glycosaminoglycan (GAG) of 498.5 mg/g creatinine (normal: 10.74-112.02). PCR analysis for recombination showed abnormal recombination in proximal and distal regions, which means IDS gene is disrupted by recombination with IDS2 gene. After 6 months of treatment: more active, decreasing of wheezing in sleep, a 6-minute walk test distance of 300 m, ultrasound showed the right live length of 111 mm, and spleen size of 89 mm, urine GAGs of 254.15 mg GAGs/g Creatinine.

Conclusions: Enzyme therapy can improve of clinical manifestation which will lead to improvements in life expectancy and quality of life in MPS II patients.

Keywords: Mucopolysaccharidosis type II; Hunter syndrome