title: Matrix Gla protein polymorphism, but not concentrations, is associated with radiographic hand osteoarthritis.
abstract: OBJECTIVE
  Factors associated with mineralization and osteophyte formation in osteoarthritis (OA) are incompletely understood. Genetic polymorphisms of matrix Gla protein (MGP), a mineralization inhibitor, have been associated clinically with conditions of abnormal calcification. We therefore evaluated the relationship of MGP concentrations and polymorphisms at the MGP locus to hand OA.
  
  
  METHODS
  Ours was an ancillary study to a 3-year randomized trial assessing the effect of vitamin K supplementation on vascular calcification and bone loss among community-dwelling elders. We studied participants who had serum MGP concentration measured and DNA genotyped for 3 MGP genetic polymorphisms (rs1800802, rs1800801, and rs4236), and who had hand radiographs. We evaluated the cross-sectional associations of serum MGP and the 3 MGP genetic polymorphisms, respectively, with radiographic hand OA using logistic regression with generalized estimating equations, adjusting for potential confounders.
  
  
  RESULTS
  Radiographic hand OA in ≥ 1 joint was present in 71% of the 376 participants (mean age 74 years, mean body mass index 28 kg/m(2), 59% women). No significant association between serum MGP concentrations and radiographic hand OA was found [adjusted OR 1.0 (ref), 1.40, 1.21, and 1.21 for quartiles 1-4, respectively]. Homozygosity of the rs1800802 minor allele was associated with 0.56 times lower prevalence of hand OA compared with having ≥ 1 major allele at this locus (95% CI 0.32-0.99, p = 0.046).
  
  
  CONCLUSIONS
  There may be an association between hand OA and genetic polymorphism at the MGP locus that is not reflected by total MGP serum concentrations. Further studies are warranted to replicate and elucidate potential mechanisms underlying these observed associations.
authors: Clinical Epidemiology Unit, Boston, Massachusetts 02118, USA. devyani.misra@bmc.org
authors: Devyani
authors: D
authors: Misra
authors: Sarah L
authors: SL
authors: Booth
authors: Micheal D
authors: MD
authors: Crosier
authors: Jose M
authors: JM
authors: Ordovas
authors: David T
authors: DT
authors: Felson
authors: Tuhina
authors: T
authors: Neogi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002135:Calcium-Binding Proteins / Q000097:blood / Q000172:deficiency / Q000235:genetics*; D003430:Cross-Sectional Studies; D016326:Extracellular Matrix Proteins / Q000097:blood / Q000172:deficiency / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease / Q000453:epidemiology / Q000235:genetics; D005820:Genetic Testing; D006225:Hand / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D008297:Male; D010003:Osteoarthritis / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000235:genetics*; D011110:Polymorphism, Genetic / Q000235:genetics*; D011859:Radiography; D000097568:Matrix Gla Protein
chemical_list: D002135:Calcium-Binding Proteins; D016326:Extracellular Matrix Proteins; D000097568:Matrix Gla Protein