title: Association between KLOTHO gene and hand osteoarthritis in a female Caucasian population.
abstract: OBJECTIVE
  Osteoarthritis (OA) is a common complex disease with strong heritable components. In this study, we investigated the association between four putatively functional genetic variants in KLOTHO gene, a strong ageing-related gene, and hand OA in a large female Caucasian population.
  
  
  METHODS
  Subjects (n=1015, age range 33-74 years) were selected from the TwinsUK Registry. Radiographs of both hands were taken for each individual with standard posteroanterior view. The presence/absence of radiographic OA, osteophyte and joint space narrowing (JSN) was assessed using a standard atlas. Four putatively functional single nucleotide polymorphisms (SNPs) in KLOTHO gene were genotyped using allelic discrimination assay. Association was initially estimated using Pearson's chi(2) or Fisher's exact test at allelic and genotypic levels. The direction and magnitude of significant association were further investigated by robust logistic regression with age as a covariate.
  
  
  RESULTS
  We found significant association between SNP G-395A and the presence/absence of radiographic hand OA and osteophyte, but not JSN. Allele G significantly increased the risk for radiographic hand OA and osteophytes with odds ratios (ORs) of 1.44 (P=0.008, 95% confidence interval (CI) 1.09-1.91) and 1.36 (P=0.006, 95% CI 1.09-1.70), respectively. From logistic regression modelling, genotype GG showed more than three-fold increased risk for both radiographic hand OA (OR=3.10, 95% CI 1.10-8.76) and osteophyte (OR=3.10, 95% CI 1.10-8.75) when compared to genotype AA. After adjustment for age, ORs for genotype GG further increased to 4.39 (P=0.006, 95% CI 1.51-12.74) for radiographic hand OA and to 4.47 (P=0.005, 95% CI 1.56-12.77) for osteophytes.
  
  
  CONCLUSIONS
  Our results suggest that one variant in KLOTHO gene is associated with the susceptibility of hand OA and appears to act through osteophyte formation rather than cartilage damage.
authors.affiliation: Twin Research and Genetic Epidemiology Unit, King's College London, St. Thomas' Hospital Campus, London, UK. feng.zhang@kcl.ac.uk
authors.forename: F
authors.initials: F
authors.lastname: Zhang
authors.forename: G
authors.initials: G
authors.lastname: Zhai
authors.forename: B S
authors.initials: BS
authors.lastname: Kato
authors.forename: D J
authors.initials: DJ
authors.lastname: Hart
authors.forename: D
authors.initials: D
authors.lastname: Hunter
authors.forename: T D
authors.initials: TD
authors.lastname: Spector
authors.forename: K R
authors.initials: KR
authors.lastname: Ahmadi
mesh_terms: D000368:Aged; D000375:Aging; D018450:Disease Progression; D004200:Diseases in Twins / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease; D005966:Glucuronidase; D050823:Hand Joints / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D000090265:Klotho Proteins; D008875:Middle Aged; D010003:Osteoarthritis / Q000235:genetics* / Q000503:physiopathology; D011859:Radiography; D044465:White People / Q000235:genetics
chemical_list: D005966:Glucuronidase; D000090265:Klotho Proteins