title: Integrin beta3 Leu33Pro polymorphism and risk of hip fracture: 25 years follow-up of 9233 adults from the general population.
abstract: OBJECTIVE
  Integrin alphavbeta3 is essential for mature osteoclast function and therefore important for the development of osteoporosis and osteoporotic fractures. Integrin alphavbeta3 antagonists have antiresorptive effects in bone. We tested the hypothesis that the Leu33Pro polymorphism in the integrin beta3-subunit associates with risk of hip fracture.
  
  
  METHODS
  We included 9233 men and women selected at random to represent the Danish general population as participants in the Copenhagen City Heart Study. First-ever hip fractures (n=267) were registered during 25 years follow-up. Log-rank statistics and Cox regression were used to compare fracture incidences and risk estimates between genotypes.
  
  
  RESULTS
  Genotyping rendered 69.9% noncarriers, 27.3% heterozygotes and 2.7% homozygotes. Incidence of hip fracture was 2.8 and 1.5 per 1000 person-years in homozygotes and noncarriers (log-rank: P=0.02), respectively. Multifactorial adjusted Cox regression revealed a hazard ratio of 2.0 (95% confidence interval: 1.1-3.5) for hip fracture in homozygotes versus noncarriers. After stratification by sex, equivalent hazard ratios were 2.0 (1.0-4.1) in women and 2.0 (0.8-5.0) in men. In the 2193 postmenopausal women, hazard ratio for hip fracture in homozygotes versus noncarriers after additional adjustment for age at menopause and use of hormone replacement therapy was 2.6 (1.2-5.3). Hazard ratio for hip fracture in heterozygotes versus noncarriers did not differ from 1.0.
  
  
  CONCLUSIONS
  Individuals homozygous for the integrin beta3 Leu33Pro polymorphism have a two-fold risk of hip fracture, mainly confined to postmenopausal women. Integrin beta3 Leu33Pro homozygosity could prove a useful marker for risk of future hip fracture and may contribute to pharmacogenetic variation in effects of integrin alphavbeta3 antagonists.
authors.affiliation: Osteoporosis Research Clinic, Department of Endocrinology, Hvidovre University Hospital, Hvidovre, Denmark.
authors.forename: Charlotte L
authors.initials: CL
authors.lastname: Tofteng
authors.forename: Pernille
authors.initials: P
authors.lastname: Bach-Mortensen
authors.forename: Stig E
authors.initials: SE
authors.lastname: Bojesen
authors.forename: Anne
authors.initials: A
authors.lastname: Tybjaerg-Hansen
authors.forename: Lars
authors.initials: L
authors.lastname: Hyldstrup
authors.forename: Børge G
authors.initials: BG
authors.lastname: Nordestgaard
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019943:Amino Acid Substitution; D015519:Bone Density / Q000235:genetics; D003718:Denmark / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006620:Hip Fractures / Q000453:epidemiology / Q000235:genetics*; D006720:Homozygote; D006801:Humans; D039661:Integrin beta3 / Q000235:genetics*; D007930:Leucine / Q000235:genetics* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D011392:Proline / Q000235:genetics* / Q000378:metabolism; D011446:Prospective Studies; D012307:Risk Factors
chemical_list: D039661:Integrin beta3; D011392:Proline; D007930:Leucine