MPSI
MPS I may hide behind seemingly unrelated signs and symptoms in your patients
When you see carpal tunnel or joint contractures, you could be seeing a patient with mucopolysaccharidosis type I (MPS I).
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MPS I disease is a rare, inherited lysosomal storage disorder that can lead to progressive accumulation of glycosaminoglycans (GAGs) throughout the body.1
The accumulated GAGs can cause cardiovascular complications and respiratory disease, which are the leading morbidities associated with early death in patients with MPS I.1
More than 80% of attenuated MPS I patients have joint contractures and are likely to see a rheumatologist.*
*According to MPS I Registry Data.
Clinical manifestations of MPS I, including the attenuated form, are chronic, progressive, and multisystemic in nature.1
MPS I includes a highly heterogeneous spectrum of severity, signs, symptoms and affected organ systems, with symptom onset in early childhood.1
NICK
Age at first symptom onset: 2 years old
Age at diagnosis: 4 years old
Joint pain and contractures are common among patients with attenuated MPS I2
Evolving joint pain and joint contractures in the absence of inflammation should always raise suspicion of an MPS disorder.2
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Understanding MPS I2
Worldwide incidence6┃1 in 100,000
MPS I is an autosomal recessive disorder caused by deficiency of α-L-iduronidase. Diagnosis is often delayed, due to the non-specific symptoms.
Test for diagnosis
• Urine test can detect abnormally high GAGs
• Diagnosis is confirmed by enzyme assay and
genetic testing
Does your patient have joint contractures?
Diagnostic algorithm2
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If you suspect MPS I disease, refer your patient to a Metabolic Specialist or Geneticist immediately.
*Newborn infants with the most severe form of MPS I (Hurler syndrome), although normal appearing, often have radiologic evidence of bone and joint abnormalities.
†Note that overall skin texture in patients with MPS I can be thickened and rough. MPS II7-8 and rarely MPS I9 can be associated with a distinctive skin lesion consisting of white “pebbly” papules 2-10 mm in diameter, sometimes coalescing in ridges.
‡We recommend both quantitative and qualitative (GAG profile) analysis in a reputable laboratory. False negatives can occur with spot screening.
Abbreviations
IDUA = α-L-iduronidase; JIA = juvenile idiopathic arthritis; RA = rheumatoid arthritis, uGAG = urinary glycosaminoglycan.
References
- Vijay S, Wraith JE. Clinical presentation and follow-up of patients with the attenuated phenotype of mucopolysaccharidosis type I. Acta Paediatr. 2005;94(7):872-877. doi:10.1111/j.1651-2227.2005.tb02004.x.
- Cimaz R, Coppa GV, Koné-Paut I, et al. Joint contractures in the absence of inflammation may indicate mucopolysaccharidosis. Pediatr Rheumatol Online J. 2009;7:18. doi:10.1186/1546-0096-7-18.
- Beck M, et al. Genet Med. 2014;16(10):759–765.
- Bruni S, Lavery C. Mol Genet Metab Rep. 2016;8:67–73.
- Donati MA, et al. Ital J Pediatr. 2018;44(Suppl 2):126.
- Muenzer J, et al. Pediatrics. 2009;123:19–29.
- Neufeld EF, Muenzer J. The mucopolysaccharidoses. Edited by: Scriver C, et al. The Metabolic and Molecular Bases of Inherited Disease. New York, NY: McGraw Hill, 2001:3421-3452.
- Martin R, Beck M, Eng C, et al. Recognition and diagnosis of mucopolysaccharidosis II (Hunter syndrome). Pediatrics. 2008;121:e377-386.
- Schiro JA, Mallory SB, Demmer L, Dowton SB, Luke MC. Grouped papules in Hurler-Scheie syndrome. J Am Acad Dermatol. 1996;35:868-870.
