title: Mitochondrial DNA haplogroups: role in the prevalence and severity of knee osteoarthritis.
abstract: OBJECTIVE
  Some studies indicate that the mitochondrion is implicated in osteoarthritis (OA). To test the hypothesis that mitochondrial DNA (mtDNA) haplogroups contribute to the prevalence and severity of knee OA, we analyzed the European mtDNA haplogroups in a Spanish population of patients with knee OA and healthy control subjects.
  
  
  METHODS
  We combined the single-base extension assay with the polymerase chain reaction-restriction fragment length polymorphism technique to obtain the different single-nucleotide polymorphisms that characterize the European haplogroups in 457 patients with knee OA and 262 radiologic controls. Knee OA radiographs had previously been classified as grades 1-4 according to Kellgren/Lawrence (K/L) scoring system.
  
  
  RESULTS
  Individuals carrying haplogroup J showed a significantly decreased risk of knee OA (odds ratio [OR] 0.460 [95% confidence interval (95% CI) 0.282-0.748], P = 0.002). In terms of K/L scores, patients carrying haplogroup J had a less severe progression of knee OA (OR 0.351 [95% CI 0.156-0.787], P = 0.012), while those carrying haplogroup U had a more severe progression (OR 1.788 [95% CI 1.094-2.922], P = 0.025).
  
  
  CONCLUSIONS
  People carrying haplogroup J may be at a lower risk of developing knee OA, and those carrying this haplogroup in whom knee OA does not develop may have a less severe progression of the disease. Patients with knee OA carrying haplogroup U may have a more severe progression of the disease. These results indicate that mtDNA haplogroups contribute to the pathogenesis of OA.
authors.affiliation: Complejo Hospitalario Universitario Juan Canalejo, A Coruña, Spain.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Rego-Pérez
authors.forename: Mercedes
authors.initials: M
authors.lastname: Fernández-Moreno
authors.forename: Carlos
authors.initials: C
authors.lastname: Fernández-López
authors.forename: Joaquín
authors.initials: J
authors.lastname: Arenas
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Blanco
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D004272:DNA, Mitochondrial / Q000235:genetics*; D018450:Disease Progression; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D006239:Haplotypes / Q000235:genetics*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D020370:Osteoarthritis, Knee / Q000208:ethnology / Q000235:genetics* / Q000503:physiopathology; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D015995:Prevalence; D012720:Severity of Illness Index; D013030:Spain
chemical_list: D004272:DNA, Mitochondrial