title: Characteristics and performance of an immunosorbent assay for human matrix Gla-protein.
abstract: BACKGROUND
  Matrix gammacarboxyglutamate (Gla)-protein (MGP) is a strong inhibitor of soft tissue calcification and is mainly produced by chondrocytes and vascular smooth muscle cells (VSMCs). MGP-deficient mice have extensive calcifications of cartilage and arteries leading to osteopenia, fractures and blood vessel ruptures. Promotor polymorphisms resulting in decreased expression levels were found to be associated with an increased risk for cardiovascular disease in humans.
  
  
  METHODS
  Recently, an ELISA-based assay has become available with which MGP may be detected in the circulation. The principle of the test kit is that of a competitive immunoassay using a monoclonal antibody against MGP bound to the microtiter plate.
  
  
  RESULTS
  Here, we report on a critical evaluation of this assay and its potential diagnostic utility in diseases associated with the degeneration of the arterial vessel wall and cartilage. The biochemical performance of the kit is satisfactory, and significant differences were found between a number of patient cohorts and the reference population. Serum MGP concentrations were significantly decreased in patients with angina pectoris and in various cartilage diseases.
  
  
  CONCLUSIONS
  The assay allows comparison of groups and may become a suitable marker for risk assessment or diagnosis in cardiovascular disease and osteoarthritis.
authors.affiliation: VitaK and Department of Biochemistry, Maastricht University, The Netherlands.
authors.forename: Leon J
authors.initials: LJ
authors.lastname: Schurgers
authors.forename: Kirsten J F
authors.initials: KJ
authors.lastname: Teunissen
authors.forename: Marjo H J
authors.initials: MH
authors.lastname: Knapen
authors.forename: Piet
authors.initials: P
authors.lastname: Geusens
authors.forename: Desiree
authors.initials: D
authors.lastname: van der Heijde
authors.forename: Martijn
authors.initials: M
authors.lastname: Kwaijtaal
authors.forename: Rob
authors.initials: R
authors.lastname: van Diest
authors.forename: Markus
authors.initials: M
authors.lastname: Ketteler
authors.forename: Cees
authors.initials: C
authors.lastname: Vermeer
mesh_terms: D000375:Aging / Q000378:metabolism; D000787:Angina Pectoris / Q000097:blood / Q000378:metabolism; D000911:Antibodies, Monoclonal; D002135:Calcium-Binding Proteins / Q000032:analysis*; D002357:Cartilage Diseases / Q000097:blood / Q000378:metabolism; D002940:Circadian Rhythm; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes; D016326:Extracellular Matrix Proteins / Q000032:analysis*; D006801:Humans; D007118:Immunoassay; D011153:Population; D011933:Reagent Kits, Diagnostic; D015203:Reproducibility of Results; D000097568:Matrix Gla Protein
chemical_list: D000911:Antibodies, Monoclonal; D002135:Calcium-Binding Proteins; D000939:Epitopes; D016326:Extracellular Matrix Proteins; D011933:Reagent Kits, Diagnostic; D000097568:Matrix Gla Protein