MPS I is a progressive condition2 that has been divided into 3 subtypes known as Hurler syndrome (MPS I-H), Hurler-Scheie syndrome (MPS I-H/S), and Scheie syndrome (MPS I-S).3 All subtypes of MPS I are caused by a deficiency of the enzyme α-L-iduronidase, which is required for the degradation of the glycosaminoglycans (GAGs) heparan sulphate and dermatan sulphate,2,4 with resulting progressive, multisystemic manifestations.2
References: 1. Beck M et al. The natural history of MPS I: global perspectives from the MPS I Registry. Genet Med.2014;16(10):759–765. 2. Clarke LA et al. Long-term efficacy and safety of laronidase in the treatment of mucopolysaccharidosis I. Pediatrics 2009;132(1):229–240. 3. Yasuda E et al. Long-term follow-up of post hematopoietic stem cell transplantation for Hurler syndrome: clinical, biochemical, and pathological improvements. Mol Genet Metab Rep 2015;2:65–76. 4. Shapiro EG et al. Neurocognition across the spectrum of mucopolysaccharidosis type I: age, severity, and treatment. Mol Genet Metab 2015;116(1-2):61–68. 5. Muenzer J et al. International Consensus Panel on the Management and Treatment of Mucopolysaccharidosis I. Mucopolysaccharidosis I: management and treatment guidelines. Pediatrics 2009;123(1):19–29. 6. Arn P et al. Characterization of surgical procedures in patients with mucopolysaccharidosis type I: findings from the MPS I Registry. J Pediatr 2009;154(6):859–864.e3. 7. Thomas JA et al. Childhood onset of Scheie syndrome, the attenuated form of mucopolysaccharidosis I. J Inherit Metab Dis 2010;33(4):421–427. 8. Semenza GL et al. Respiratory complications of mucopolysaccharide storage disorders. Medicine 1988;67(4):209–219. 9. Clarke LA et al. Mucopolysaccharidosis type I. In: Pagon RA et al eds. GeneReviews® Seattle, WA: University of Washington, Seattle; 2002. http://www.ncbi.nlm.nih.gov/books/NBK1162/?report=reader. Accessed July 31, 2015. 10. de Ru MH et al. Enzyme replacement therapy and/or hematopoietic stem cell transplantation at diagnosis in patients with mucopolysaccharidosis type I: results of a European consensus procedure. Orphanet J Rare Dis. 2011;6(55):1–9.