1<\/sup><\/h2>\nWhile each subtype of MPS disorder is clinically distinct, all feature the life-limiting, progressive, multisystemic disease manifestations common to MPS disease pathology.2,3,4,5<\/sup> Management of patients with MPS requires an understanding of the specific clinical manifestations and management recommendations for each MPS subtype.2,6<\/sup><\/p>\n <\/div>\n <\/div>\n <\/div>\n<\/div>\n\n\n
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MPS I<\/h2>\n
Disease name: Hurler, Hurler\/Scheie, Scheie<\/strong> | Deficient enzyme: \u03b1-L-iduronidase<\/strong> | Gene symbol: IDUA<\/em><\/strong><\/p>\nPatients with Mucopolysaccharidosis Type I (MPS I) are at increased risk for severe morbidity and early mortality1<\/sup><\/h3>\nMPS I is a progressive condition2<\/sup> 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<\/sup> All subtypes of MPS I are caused by a deficiency of the enzyme \u03b1-L-iduronidase, which is required for the degradation of the glycosaminoglycans (GAGs) heparan sulphate and dermatan sulphate,2,4<\/sup> with resulting progressive, multisystemic manifestations.2<\/sup><\/p>\n\n- MPS I-H typically presents within the first 2 years of life with developmental delay, cognitive decline and rapid progression1,2<\/sup><\/li>\n
- MPS I-H\/S typically presents between the ages of 3 and 7 with mild or absent cognitive decline and slower progression1,2<\/sup><\/li>\n
- MPS I-S typically presents between the ages of 5 and 13 with no cognitive decline and slower progression1,2<\/sup><\/li>\n<\/ul>\n <\/div>\n <\/div>\n <\/div>\n<\/div>\n\n
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<\/span>\n <\/span>\n <\/div>\n Observed presentation\n<\/h2>\n <\/div>\n \n
\n- Symptoms appear at varying ages depending on the specific enzyme deficiency and rate of disease progression:1<\/sup>\n
\n- H, ages 0 to 2<\/li>\n
- H\/S, ages 3 to 7<\/li>\n
- S, ages 5 to 13<\/li>\n<\/ul>\n<\/li>\n
- Observed presentation includes:5<\/sup>\n
\n- Change in facial features<\/li>\n
- Restricted joint movement<\/li>\n
- Skeletal deformity<\/li>\n
- Macrocephaly<\/li>\n
- Frequent respiratory infections<\/li>\n
- Cardiomyopathy<\/li>\n
- Recurrent ear infections<\/li>\n
- Hernias<\/li>\n
- Kyphosis\/gibbus deformity<\/li>\n<\/ul>\n<\/li>\n
- Specific recommendations for consideration of MPS I include:6<\/sup>\n
\n- Children with gibbus deformity, enlarged tongue, and\/or 2 or more surgeries before 18 months should prompt diagnostic testing<\/li>\n
- Children over 2 years of age with claw hands, cardiac problems and\/or 2 or more surgeries before age 10 should prompt diagnostic testing<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n <\/div>\n <\/div>\n
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<\/span>\n <\/span>\n <\/div>\n Disease progression\n<\/h2>\n <\/div>\n \n
\n- Overall disease burden:\n
\n- Patients experience multiorgan dysfunction and have a high disease burden1<\/sup><\/li>\n
- This progressive, debilitating disease also puts psychological and financial burdens on patients and their families5<\/sup><\/li>\n<\/ul>\n<\/li>\n
- Hurler (H):\n
\n- Symptoms appear shortly after birth, progress rapidly, and typically include:1<\/sup>\n
\n- Developmental delay and cognitive decline<\/li>\n
- Coarse facial features<\/li>\n
- Joint stiffness and contractures<\/li>\n
- Short stature<\/li>\n
- Hepatosplenomegaly<\/li>\n
- Respiratory and cardiac disease<\/li>\n<\/ul>\n<\/li>\n
- Left untreated, patients typically die within the first decade of life, often due to cardiorespiratory failure and neurological disease1,5<\/sup><\/li>\n<\/ul>\n<\/li>\n
- Hurler-Scheie (H\/S) and Scheie (S):\n
\n- Symptom presentation varies according to age7<\/sup>:\n
\n- Hernia typically occurs before age 5<\/li>\n
- Joint contractures and dysostosis multiplex typically arise between the ages of 5 and 12<\/li>\n
- Scoliosis, carpal tunnel syndrome, and congestive heart failure often occur in adolescence<\/li>\n
- Glaucoma, cardiomyopathy, and myelopathy typically arise in early adulthood<\/li>\n<\/ul>\n<\/li>\n
- Left untreated, patients with MPS I-H\/S typically die within the second or third decade of life1<\/sup><\/li>\n
- Left untreated, patients with MPS I-S usually sustain significant morbidity1<\/sup><\/li>\n<\/ul>\n<\/li>\n
- Patients with MPS I have a high surgical burden, which may include:6<\/sup>\n
\n- Myringotomies<\/li>\n
- Hernia surgery, often with repeat procedures<\/li>\n
- Adenoidectomy<\/li>\n
- Tonsillectomy<\/li>\n
- Ventriculoperitoneal shunt<\/li>\n
- Spinal procedures<\/li>\n
- Carpal tunnel surgery<\/li>\n
- Orthopaedic surgeries of hip, knee and foot<\/li>\n<\/ul>\n<\/li>\n
- Because patients with MPS I often experience anaesthetic complications due to obstructed airways, special care must be taken when undergoing surgery8<\/sup><\/li>\n<\/ul>\n <\/div>\n <\/div>\n
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<\/span>\n <\/span>\n <\/div>\n Genetic information\n<\/h2>\n <\/div>\n \n
\n- MPS I is caused by pathogenic variants in the \u03b1-L-iduronidase gene, IDUA<\/em>4<\/sup><\/li>\n
- There are over 100 known pathogenic variants within IDUA<\/em>9<\/sup><\/li>\n
- These pathogenic variants lead to accumulation of the GAGs heparan and dermatan sulphate4<\/sup><\/li>\n<\/ul>\n <\/div>\n <\/div>\n
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<\/span>\n <\/span>\n <\/div>\n Key management considerations\n<\/h2>\n <\/div>\n \n
\n- The potential use of enzyme replacement therapy and hematopoietic stem cell transplantation (HSCT) are both important considerations in the management of MPS I:1,5<\/sup><\/li>\n
- Patients with the Hurler phenotype diagnosed before 2.5 years should be treated with HSCT10<\/sup><\/li>\n
- All other patients should be treated with enzyme replacement therapy.10<\/sup><\/li>\n
- Available treatment guidelines include:\n
\n- Martins AM et al<\/em>. Guidelines for the management of mucopolysaccharidosis type I. J Pediatr<\/em> 2009;155(4)(suppl 2):S32\u2013S46.<\/li>\n
- Muenzer J et al<\/em>.\u00a0International Consensus Panel on the Management and Treatment of Mucopolysaccharidosis I. Mucopolysaccharidosis I: management and treatment guidelines. Pediatrics <\/em>2009;123(1):19\u201329.<\/li>\n
- de Ru MH et al<\/em>. 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<\/em> 2011;6(55):1\u20139.<\/li>\n
- Langereis EJ et al<\/em>. Treatment of hip dysplasia in patients with mucopolysaccharidosis type I after hematopoietic stem cell transplantation: results of an international consensus procedure. Orphanet J Rare Dis<\/em> 2013;8(155):1\u201316.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n <\/div>\n <\/div>\n
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<\/span>\n <\/span>\n <\/div>\n References:\n<\/h2>\n <\/div>\n \n
1. Beck M et al<\/em>. The natural history of MPS I: global perspectives from the MPS I Registry. Genet Med<\/em>.2014;16(10):759\u2013765.
\n2. Clarke LA et al<\/em>. Long-term efficacy and safety of laronidase in the treatment of mucopolysaccharidosis I. Pediatrics<\/em> 2009;132(1):229\u2013240.
\n3. Yasuda E et al<\/em>. Long-term follow-up of post hematopoietic stem cell transplantation for Hurler syndrome: clinical, biochemical, and pathological improvements. Mol Genet Metab Rep<\/em> 2015;2:65\u201376.
\n4. Shapiro EG et al<\/em>. Neurocognition across the spectrum of mucopolysaccharidosis type I: age, severity, and treatment. Mol Genet Metab<\/em> 2015;116(1-2):61\u201368.
\n5. Muenzer J et al<\/em>. International Consensus Panel on the Management and Treatment of Mucopolysaccharidosis I. Mucopolysaccharidosis I: management and treatment guidelines. Pediatrics<\/em> 2009;123(1):19\u201329.
\n6. Arn P et al<\/em>. Characterization of surgical procedures in patients with mucopolysaccharidosis type I: findings from the MPS I Registry. J Pediatr<\/em> 2009;154(6):859\u2013864.e3.
\n7. Thomas JA et al<\/em>. Childhood onset of Scheie syndrome, the attenuated form of mucopolysaccharidosis I. J Inherit Metab Dis<\/em> 2010;33(4):421\u2013427.
\n8. Semenza GL et al<\/em>. Respiratory complications of mucopolysaccharide storage disorders. Medicine<\/em> 1988;67(4):209\u2013219.
\n9. Clarke LA et al<\/em>. Mucopolysaccharidosis type I. In: Pagon RA et al eds. GeneReviews\u00ae<\/em> Seattle, WA: University of Washington, Seattle; 2002. http:\/\/www.ncbi.nlm.nih.gov\/books\/NBK1162\/?report=reader. Accessed June, 2023.
\n10. de Ru MH et al<\/em>. 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<\/em>. 2011;6(55):1\u20139.<\/small><\/p>\n <\/div>\n <\/div>\n \t\t<\/div>\n\t<\/div>\n<\/div>\n\n\n
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MPS II<\/h2>\n
Disease name: Hunter<\/strong> | Deficient enzyme: Iduronate 2-sulphatase<\/strong> | Gene symbol: IDS<\/strong><\/em><\/p>\nPatients with Mucopolysaccharidosis Type II (MPS II) are at elevated risk for severe morbidity and early mortality16<\/sup><\/h3>\nMPS II, also known as Hunter syndrome, is caused by a genetic pathogenic variant in the iduronate 2-sulphatase (IDS<\/em>) gene leading to deficient cleavage of glycosaminoglycans (GAGs), heparan and dermatan sulphate, which leads to intracellular progressive GAG accumulation with resulting progressive, multisystemic disease.1,2<\/sup><\/p>\n\n- The rapidly progressing form of MPS II typically presents between 18 and 36 months of age with cognitive dysfunction and severe somatic changes1,2<\/sup><\/li>\n
- The slowly progressing form of MPS II typically presents between the ages of 4 and 8 years with no cognitive decline and mild somatic changes1,2<\/sup><\/li>\n<\/ul>\n <\/div>\n <\/div>\n <\/div>\n<\/div>\n\n
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<\/span>\n <\/span>\n <\/div>\n Observed presentation\n<\/h2>\n <\/div>\n \n
\n- Symptoms appear at varying ages2<\/sup><\/li>\n
- Observed presentation includes the following:3<\/sup>\n
\n- Change of facial features<\/li>\n
- Enlarged tongue<\/li>\n
- Macrocephaly<\/li>\n
- Hypertrophic tonsils and adenoids<\/li>\n
- Irregularly shaped teeth<\/li>\n
- Recurrent ear infections<\/li>\n
- Hernias<\/li>\n
- Pebbled skin<\/li>\n
- Short stature<\/li>\n
- Joint contractures<\/li>\n
- Changes to musculoskeletal system, eyes, gastrointestinal tract, airways and cardiovascular system<\/li>\n<\/ul>\n<\/li>\n
- Combinations of the above clinical manifestations should prompt testing for MPS II3<\/sup><\/li>\n
- There is a high prevalence of MPS II in the Ashkenazi Jewish population4<\/sup><\/li>\n
- MPS II is an X-linked recessive disorder, therefore mainly affecting males2<\/sup><\/li>\n<\/ul>\n <\/div>\n <\/div>\n
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<\/span>\n <\/span>\n <\/div>\n Disease progression\n<\/h2>\n <\/div>\n \n
\n- Overall disease burden:\n
\n- Patients with the rapidly progressing form of disease experience multiorgan dysfunction, resulting in high disease burden2<\/sup><\/li>\n
- Patients with the slowly progressing form of disease may present with symptoms and complications that lead to significant morbidity and disability2<\/sup><\/li>\n
- Both forms of the disease are associated with severe psychological and financial burdens for patients and their families3,5<\/sup><\/li>\n<\/ul>\n<\/li>\n
- Rapidly progressing MPS II:\n
\n- Symptoms may include: 1,2<\/sup>\n
\n- Cognitive decline with hyperactive and aggressive behaviour<\/li>\n
- Hernia<\/li>\n
- Significant multisystemic complications, including skeletal deformities that can restrict pulmonary function 2,5<\/sup><\/li>\n<\/ul>\n<\/li>\n
- Left untreated, patients typically die before 15 years of age; mortality is often associated with cardiorespiratory failure and neurological deterioration. 1,2<\/sup><\/li>\n<\/ul>\n<\/li>\n
- Slowly progressing MPS II:\n
\n- Symptoms appear between 4 and 8 years of age with variable progression and typically include:2<\/sup>\n
\n- Short stature<\/li>\n
- Coarse facial features<\/li>\n
- Joint contractures<\/li>\n
- Hernia due to hepatosplenomegaly<\/li>\n<\/ul>\n<\/li>\n
- Left untreated, patients typically die between the ages of 20 and 60 years of age; mortality is often associated with cardiorespiratory failure. 1,2<\/sup><\/li>\n<\/ul>\n<\/li>\n
- Patients with MPS II typically have a high surgical burden that may include:2,3<\/sup>\n
\n- Myringotomies<\/li>\n
- Hernia surgery, often with repeat procedures<\/li>\n
- Adenoidectomy<\/li>\n
- Tonsillectomy<\/li>\n
- Cervical decompression<\/li>\n
- Carpal tunnel surgery<\/li>\n
- Cardiac valve replacement therapy<\/li>\n
- Hip and knee replacement and correction of lower limb axis<\/li>\n<\/ul>\n<\/li>\n
- Patients with MPS II often experience anaesthetic complications due to obstructed airways; therefore, care must be taken for patients undergoing surgery2,3<\/sup><\/li>\n<\/ul>\n <\/div>\n <\/div>\n
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<\/span>\n <\/span>\n <\/div>\n Genetic information\n<\/h2>\n <\/div>\n \n
\n- MPS II is caused by pathogenic variants in the