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What is MPS?

MPS disorders are a group of rare, genetic, inheritable, metabolic diseases, which form part of the lysosomal storage diseases (LSDs)1-4

  • They affect males and females equally (with the exception of MPS II, which mainly affects males) and can be as common as ~1 in 25,000 live births (with prevalence varying by region and ethnic background)3,5
  • MPS disorders are caused by a deficiency in enzymes responsible for degrading glycosaminoglycans (GAGs).  As a result, GAGs accumulate in the lysosomes of many of the bodys cells, causing progressive damage throughout the body1-4
  • Multiple organs and systems can be involved, including the cardiovascular, skeletal, respiratory and neurological systems3
  • Having an MPS disorder can lead to organ failure, cognitive impairment and reduced life expectancy3,4

Discover the pathology behind the presentation

MPS disorders exhibit similar pathologies and mechanisms, regardless of the specific enzyme deficiency:1,6

  • Lysosomal enzymes break down glycosaminoglycans (GAGs)1,6
  • Accumulation of GAGs throughout the body causes progressive damage manifesting in a range of multisystemic consequences1,6
Play

Watch how MPS affects patients from the inside out

As an example, this video illustrates the mechanism of disease for Morquio A (MPS IVA).

To date, 11 different enzymatic deficiencies are known to cause seven MPS disorders:2,4

Types of MPS

Recognise the possibility – raise your suspicion

In many genetic conditions, diagnostic delay is common due to lack of clinical suspicion.

Many patients with mucopolysaccharidosis (MPS) disorders experience significant diagnostic delay because of disease rarity, phenotypic heterogeneity, and a myriad of seemingly unrelated symptoms associated with the disease.1,7,8 In a survey of patients with rare diseases (N=920) sponsored by the Global Genes Project, the mean reported length of time from symptom onset to accurate diagnosis was 4.8 years, with a range of 0 to 20 years.9

The emergence of specific therapies for some MPS disorders has increased the need for accurate and early diagnosis.1,11,12-14 Any delay in diagnosis or treatment may result in:

  • Serious systemic complications15,16
  • Irreversible organ damage12
  • Delay in initiating enzyme replacement therapy (ERT) to address underlying enzyme deficiency7
  • Lack of access to disease-specific management, with concomitant increase in risk of surgical mortality1,3,13,14,17

Since treatment exists for a number of MPS disorders, delay in diagnosis can mean delay in therapy and/or delay in disease-specific management.3,13,14

MPS: hiding in plain sight

Early recognition hinges on early suspicion

MPS disorders are clinically heterogeneous and result in serious complications regardless of the rate of progression, which can range from slowly to rapidly progressing. While rates of progression are gross characterisations of disease severity, patients with slowly progressing disease are also at risk for the serious morbidities and mortality commonly associated with rapidly progressing disease.7,3,18

  • If untreated, many individuals with severe disease do not live far into adulthood (second and third decade)3,19
  • Individuals with slowly progressing disease typically present with symptoms later in life18,20

Patients with MPS can present with classical or non-classical patterns of signs and symptoms.20

  • Classical symptomology may present as more easily recognisable patterns of signs and symptoms that have been extensively documented in literature and in clinical practice20
  • Non-classical symptomology may present more subtly – without the distinct facial features, short stature or obvious musculoskeletal involvement of classical forms of MPS – making this phenotype more difficult to distinguish from other, more common skeletal or metabolic disorders20
  • As an example, recent research has indicated that approximately 25% of patients with Morquio A syndrome (MPS IVA) present with a non-classical phenotype21
Image of two non classical patients

Images depict non-classical MPS patient (top) and classical MPS patient (bottom)

Irrespective of phenotype, symptoms of MPS can progress into end-organ damage16

Take a closer look at the signs and symptoms

Patients with MPS are diverse – discover the full spectrum

In your everyday practice, diverse presentations can complicate patient identification.

The best way to accurately diagnose MPS is to refer a patient to a geneticist who is familiar with MPS and knows how to confirm the diagnosis.1,22

You should suspect MPS when confronted by patients who:

  • Exhibit any number or pattern of heterogeneous and seemingly unrelated signs1,22
  • Have high surgical needs and burdens1,22

When you suspect MPS, refer immediately to a geneticist or metabolic centre.1,22 Read more about testing and assessment.

Early identification relies on seeing the full clinical picture and knowing the key clinical hallmarks of MPS.1,3,7,14,22

Assessing MPS

Optimise outcomes – change the clinical course for your patients

An optimal care-delivery model for MPS disorders

Decades of disease and therapeutic research and practice have culminated in new approaches to clinical management of MPS disorders. At the centre of today’s new era of management is – a coordinated, multidisciplinary care-delivery model.3,23-24

MPS care team diagram

The unique risks and needs associated with these multisystemic, complex conditions are best addressed by coordinating ERT (if available) with the care-delivery model, creating three pillars of care.3,7,12,25-27

As the management paradigm continues to evolve, changes in best practices and strategies continue to show greater promise for the patients and families affected by the disorders.12,23

Prompt referral for diagnosis is essential to optimise care for patients with MPS.1,3,7

Managing MPS

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References:

  1. Lehman TJ et al. Rheumatology (Oxford). 2011;50(Suppl 5):v41–v48.
  2. Neufeld EF et al. The Metabolic and Molecular Bases of Inherited Disease. McGraw-Hill, New York 2001;8:3421−52.
  3. Muenzer J. Rheumatology (Oxford). 2011;50:v4–v12.
  4. Beck M et al. J Pediatr Rehabil Med. 2010;3(1):39−46.
  5. Gokdoǧan C et al. Braz J Otorhinolaryngol. 2016;82(3):281−284.
  6. Muenzer J, Beck M, Eng CM, et al.Genet Med. 2011;13(2):95–101. doi:10.1097/GIM.0b013e3181fea459.
  7. Hendriksz C. Improved diagnostic procedures in attenuated mucopolysaccharidosis. Br J Hosp Med 2011;72(2):91–95.
  8. Hendriksz CJ et al. Clinical overview and treatment options for non-skeletal manifestations of mucopolysaccharidosis type IVA. J Inherit Metab Dis 2013;36(2):309–322.
  9. Engel PA et al. Physician and patient perceptions regarding physician training in rare diseases: the need for stronger educational initiatives for physicians. J Rare Disord 2013;1(2):1–15.
  10. Clarke LA et al. Biomarkers for the mucopolysaccharidoses: discovery and clinical utility. Mol Genet Metab 2012;106(4):396–402.
  11. Muenzer J. Early initiation of enzyme replacement therapy for the mucopolysaccharidoses. Mol Genet Metab 2014;111(2):63–72.
  12. 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.
  13. Clarke LA. Pathogenesis of skeletal and connective tissue involvement in the mucopolysaccharidoses: glycosaminoglycan storage is merely the instigator. Rheumatology (Oxford). 2011;50(suppl 5):v13–18.
  14. Morishita K, Petty RE. Musculoskeletal manifestations of mucopolysaccharidoses. Rheumatology 2011;50(suppl 5):v19–v25.
  15. Hendriksz CJ et al. International guidelines for the management and treatment of Morquio A syndrome. Am J Med Genet Part A 2014;9999A:1–15.
  16. Berger KI et al. Respiratory and sleep disorders in mucopolysaccharidosis. J Inherit Metab Dis 2013;36(2):201–210.
  17. Spinello CM et al. Anesthetic management in mucopolysaccharidoses. ISRN Anesthesiol 2013;2013:1–10.
  18. Lampe C. Attenuated mucopolysaccharidosis: are you missing this debilitating condition? Rheumatology (Oxford). 2012;51(3):401–402.
  19. Tomatsu S et al. Mucopolysaccharidosis type IVA (Morquio A disease): clinical review and current treatment: a special review. Curr Pharm Biotechnol 2011;12(6):931–945.
  20. Lachman RS et al. Mucopolysaccharidosis IVA (Morquio A syndrome) and VI (Maroteaux-Lamy syndrome): under-recognized and challenging to diagnose. Skeletal Radiol 2014;43(3):359–369.
  21. Montaño AM et al. International Morquio A Registry: clinical manifestation and natural course of Morquio A disease. J Inherit Metab Dis 2007;30(2):165–174.
  22. Muenzer J. The mucopolysaccharidoses: a heterogeneous group of disorders with variable pediatric presentations. J Pediatr 2004;144(suppl 5):S27–S34.
  23. Kakkis ED. Enzyme replacement therapy for the mucopolysaccharide storage disorders. Expert Opin Investig Drugs 2002;11(5):675–685.
  24. Agency for Healthcare Research and Quality. Defining the PCMH. https://pcmh.ahrq.gov/page/defining-pcmh. Accessed December 15, 2015.
  25. Hwu W-L et al. Current diagnosis and management of mucopolysaccharidosis VI in the Asia-Pacific region. Mol Genet Metab 2012;107(1-2):136–144.
  26. Klitzner TS et al. Benefits of care coordination for children with complex disease: a pilot medical home project in a resident teaching clinic. J Pediatr 2010;156(6):1006–1010.
  27. Mosquera RA et al. Effect of an enhanced medical home on serious illness and cost of care among high-risk children with chronic illness: a randomized clinical trial. JAMA 2014;312(24):2640–2648.