Early response to idursulfase treatment in a 3 year-old boy affected of Hunter syndrome

Department of Pediatrics, Hospital Materno-Infantil-Hospital Infanta Cristina, Facultad de Medicina, Avda Damian Tellez Lafuente s/n, 06010 UEX Badajoz, Spain
European Journal of Medical Genetics (Impact Factor: 1.47). 05/2008; 51(3):268-71. DOI: 10.1016/j.ejmg.2008.02.005
Source: PubMed


We present a 3-year-old boy affected with Hunter syndrome. When we first evaluated the patient glycosaminoglycans (GAG) in urine were elevated (94.6 ng/nmol/creatinine); the enzyme activity determined in serum was decreased (3.9 nmol/hxml) and the mutation found was N350H, exon 8. His clinical signs were coarse facial features, hepatomegaly (6 cm), splenomegaly (6 cm), elbow stiffness and hypospadias; dilatation of the perivascular spaces and white matter abnormalities, mitral regurgitation. After two weeks on enzyme replacement therapy (ERT) with idursulfase (IDS), the excretion of GAG was decreased to 36.2 ng/nmol/creatinine and the liver and spleen volumes were reduced to normal limits. He was subsequently noted to have a softer, finer skin, he had no further bouts of bronchitis, and his physical activity improved. This indicates that IDS in young children is well tolerated and that it has several effects which may confer clinical benefits with long-term therapy.

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    ABSTRACT: Hunter syndrome (mucopolysaccharidosis type II [MPS II], OMIM309900) is a rare X-linked lysosomal storage disorder caused by deficiency of the enzyme iduronate-2-sulphatase, resulting in accumulation of glycosaminoglycans (GAGs), multisystem organ failure and early death. Enzyme replacement therapy (ERT) with idursulfase is commercially available since 2007. Early access programs were established since 2005. However, limited information on the effects of ERT in young children is available to date. The aim of this analysis was therefore to determine the effects of ERT on patients younger than 5 years of age. We report data from six Spanish patients with confirmed Hunter syndrome who were younger than 5 years at the start of ERT, and had been treated with weekly intravenous infusions of idursulfase between 6 and 14 months. Baseline and treatment data were obtained from the Hunter Outcome Survey (HOS). HOS is an international database of MPS II patients on ERT or candidates to be treated, that collects data in a registry manner. HOS is supported by Shire Human Genetic Therapies, Inc. (Cambridge, MA, USA). At baseline, all patients showed neurological abnormalities, including ventriculomegaly, hydrocephaly, cerebral atrophy, perivascular changes and white matter lesions. Other signs and symptoms included thoracic deformity, otitis media, joint stiffness and hepatosplenomegaly, demonstrating that children under 5 years old can also be severely affected. ERT reduced urinary GAG levels, and reduced spleen (n = 2) and liver size (n = 1) after only 8 months. Height growth was maintained within the normal range during ERT. Joint mobility either stabilized or improved during ERT. In conclusion, this case series confirms the early onset of signs and symptoms of Hunter syndrome and provides the first evidence of ERT beneficial effects in patients less than 5 years of age. Similar efficacy and safety profiles to those seen in older children can be suggested, although further studies including a direct comparison with older patients would still be required.
    European journal of medical genetics 11/2010; 53(6):371-7. DOI:10.1016/j.ejmg.2010.07.013 · 1.47 Impact Factor
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    ABSTRACT: To use the Hunter Outcome Survey, an international database, to assess the safety and effectiveness of enzyme replacement therapy with idursulfase in patients with Hunter syndrome who started treatment before 6 years of age. The study population included all patients enrolled in the Hunter Outcome Survey who started idursulfase infusions (0.5 mg/kg every other week) before 6 years of age and who had at least one follow-up examination recorded. The study population included 124 patients, younger than 6 years, who had a mean age at start of idursulfase of 3.6 ± 1.6 years (mean ± SD). The mean duration of treatment was 22.9 ± 14.6 months. A total of 69 infusion-related reactions occurred in 33 (26.6%) patients, including three serious infusion-related reactions occurring in a single patient. After at least 6 months of idursulfase, urine glycosaminoglycan levels decreased from 592 ± 188 to 218 ± 115 μg/mg creatinine (P < 0.0001, n = 34). Liver size, estimated by palpation, was also significantly decreased (P = 0.005, n = 23). Similar safety and effectiveness results were seen in patients who were aged 6 years or older when initiating idursulfase. No new safety concerns were identified in patients younger than 6 years, and clinical benefit was suggested by the reduction in liver size.
    Genetics in medicine: official journal of the American College of Medical Genetics 02/2011; 13(2):102-9. DOI:10.1097/GIM.0b013e318206786f · 7.33 Impact Factor
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    ABSTRACT: Hunter syndrome or mucopolysaccharidosis II (MPS II) is a rare X-linked disease caused by a deficiency of the iduronate-2-sulphatase (12S) lysosomal enzyme, resulting in a progressive accumulation of glycosaminoglycans (GAGs). Enzyme replacement therapy (ERT) with recombinant human 12S idursulfase has been used infrequently in children < 5 years. We present the case of a 7 years and 10 months-old child, who was diagnosed with a severe form of MPS II at the age of 3 years, and who began a 36 months' treatment with idursulfase at 4 years 10 months. After 10 months, GAG urinary excretion was normal, but after just 4 months the liver and spleen had decreased in size, returning to normal limits by 36 months. Significant bone remodeling was noted after 16 months. Cardiac and neurological development, however, progressively deteriorated. The only adverse reactions were episodic inflammations of the upper and/or lower respiratory tract, but there was no otitis. Early use of ERT, presuming good treatment adherence, can significantly improve bone abnormalities.
    European review for medical and pharmacological sciences 03/2011; 15(3):253-8. · 1.21 Impact Factor
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