Enzyme Replacement Therapy in Mucopolysaccharidosis II Patients Under 1 Year of Age
Mucopolysaccharidosis (MPS) II, or Hunter syndrome, is a lysosomal storage disease characterized by multi-systemic involvement and a progressive clinical course. Enzyme replacement therapy with idursulfase has been approved in more than 50 countries worldwide; however, safety and efficacy data from clinical studies are currently only available for patients 1.4 years of age and older. Sibling case studies of infants with MPS I, II, and VI who initiated ERT in the first weeks or months of life have reported no new safety concerns and a more favorable clinical course for the sibling treated in infancy than for the later-treated sibling. Here we describe our experiences with a case series of eight MPS II patients for whom idursulfase treatment was initiated at under 1 year of age. The majority of the patients were diagnosed because of a family history of disease. All of the infants displayed abnormalities consistent with MPS II at diagnosis. The youngest age at treatment start was 10 days and the oldest was 6.5 months, with duration of treatment varying between 6 weeks and 5.5 years. No new safety concerns were observed, and none of the patients experienced an infusion-related reaction. All of the patients treated for more than 6 weeks showed improvements and/or stabilization of some somatic manifestations while on treatment. In some cases, caregivers made comparisons with other affected family members and reported that the early-treated patients experienced a less severe clinical course, although a lack of medical records for many family members precluded a rigorous comparison.
KeywordsHematopoietic Stem Cell Transplantation Carpal Tunnel Syndrome Enzyme Replacement Therapy Pectus Excavatum Mild Hearing Loss
Enzyme replacement therapy
Hematopoietic stem cell transplantation
Lysosomal storage disorder
Magnetic resonance imaging
We would like to thank all the patients and families for their participation. Editorial assistance to the authors was provided by Jillian Lokere, MS, of The Curry Rockefeller Group, LLC, Tarrytown, New York, and was funded by Shire. The authors received no payment for their work, and they confirm independence from the funding source.
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