MPS I (Mucopolysaccharidosis I)
Take on the Challenge of Diagnosis
Do you see patients with:
- Recurrent ENT symptoms
- Joint stiffness/contractures
- Enlarged liver
- Scoliosis/kyphosis
It could be MPS I, a progressive, multisystemic, often life-threatening genetic disorder.
MPS I is caused by a deficiency of alpha-L-iduronidase (IDUA), a lysosomal enzyme involved in the degradation of certain glycosaminoglycans (GAGs).GAGs are complex polysaccharides that are important components of the extracellular matrix and connective tissues. IDUA deficiency leads to accumulation of GAGs, resulting in cell, tissue, and organ dysfunction.
If you suspect you have a patient with MPS I, laboratory tests can aid in diagnosis.
Urinary GAG (analyte) test: The presence of urinary GAGs indicates reduced IDUA activity, which is a hallmark of MPS I. However, in attenuated forms of the disease, where some residual IDUA activity remains, the urinary GAG test may be negative or inconclusive. Therefore, the results of this test alone are not definitive.1,2
Iduronidase Activity Assay: Fibroblasts taken from a patient suspected to have MPS I are tested for endogenous IDUA activity by use of a fluorometric enzyme activity assay. The sensitivity of this assay allows for the definitive diagnosis of MPS I.3
For more information on MPS I diagnosis call Genzyme Medical Information at 800-745-4447 (option 2).
GeneTests.org is a resource for finding diagnostic laboratories.
Genzyme, one of the world's leading biotechnology companies, is a proud supporter of Focus on Children's Health, on ReachMD, XM channel 160 and ReachMD.com. Genzyme does not control the editorial content of this programming. The views expressed are solely those of the guests who are selected by ReachMD.
Hear more from
Chet Whitley, PhD, MD
Director, Advanced Therapies
Department of Pediatrics and Institute of Human Genetics
University of Minnesota
Dr. Whitley and his patient Allison were featured during Children's Health Month on XM 160. Hear more about Dr. Whitley's experience with MPS I:
Allison's presentation (1:35) Clinical presentation of MPS I (2:14) Diagnosing MPS I (0:52) Managing patients with MPS I (1:41)Learn more about MPS I at MPSIdisease.com
References
1. Vijay S, Wraith JE. Clinical presentation and follow-up of patients with the attenuated phenotype of mucopolysaccharidosis type I. Acta Paediatr 2005;94:872-87.
2. Cimaz R, Vijay S, Haase C, et al. Attenuated type I mucopolysaccharidosis in the differential diagnosis of juvenile idiopathic arthritis: a series of 13 patients with Scheie syndrome. Clin Exp Rheumatol 2006;24:196-202.
3. Hall CW, Liebaers I, Di Natale P, Neufeld EF. Enzymic diagnosis of the genetic mucopolysaccharide storage disorders. Methods Enzymol. 1978;50:439-456.