title: Influence of vitamin D receptor genotype on bone mineral density in postmenopausal women: a twin study in Britain.
abstract: OBJECTIVE
  To investigate the possible association between vitamin D receptor genotype and bone mineral density in a large group of postmenopausal twins.
  
  
  METHODS
  Cross sectional twin study.
  
  
  METHODS
  Twin population based in Britain.
  
  
  METHODS
  95 dizygotic (non-identical) pairs of twins and 87 monozygotic (identical) pairs of twins aged 50-69 years, postmenopausal, and free of diseases affecting bone, recruited from a national register of twins and with a media campaign.
  
  
  METHODS
  Bone mineral density measured at the hip, lumbar spine, forearm, and for the whole body by dual energy x ray absorptiometry in relation to differences in the vitamin D receptor genotype.
  
  
  RESULTS
  At all sites the values of bone density among dizygotic twins were more similar in those of the same vitamin D receptor genotype than in those of differing genotype, and the values in the former were closer to the correlations seen in monozygotic twins. Women with the genotype that made them at risk of osteoporotic fracture had an adjusted bone mineral density that was significantly lower by SD 0.5 to 0.6 at the hip, lumbar spine, and for the whole body. The results could not be explained by differences in age, weight, years since menopause, or use of hormone replacement therapy.
  
  
  CONCLUSIONS
  The findings that in postmenopausal women in Britain bone density-particularly at the hip and spine-is genetically linked and specifically associated with the vitamin D receptor genotypes should lead to novel approaches to the prevention and treatment of osteoporosis.
authors.affiliation: Rheumatology Department, United Medical and Dental School, St Thomas's Hospital, London.
authors.forename: T D
authors.initials: TD
authors.lastname: Spector
authors.forename: R W
authors.initials: RW
authors.lastname: Keen
authors.forename: N K
authors.initials: NK
authors.lastname: Arden
authors.forename: N A
authors.initials: NA
authors.lastname: Morrison
authors.forename: P J
authors.initials: PJ
authors.lastname: Major
authors.forename: T V
authors.initials: TV
authors.lastname: Nguyen
authors.forename: P J
authors.initials: PJ
authors.lastname: Kelly
authors.forename: J R
authors.initials: JR
authors.lastname: Baker
authors.forename: P N
authors.initials: PN
authors.lastname: Sambrook
authors.forename: J S
authors.initials: JS
authors.lastname: Lanchbury
mesh_terms: D015502:Absorptiometry, Photon; D000368:Aged; D001483:Base Sequence; D015519:Bone Density / Q000235:genetics*; D003430:Cross-Sectional Studies; D004247:DNA / Q000032:analysis; D005260:Female; D005542:Forearm / Q000502:physiology; D005819:Genetic Markers; D005838:Genotype; D006801:Humans; D008159:Lumbar Vertebrae / Q000502:physiology; D008875:Middle Aged; D008969:Molecular Sequence Data; D017698:Postmenopause / Q000235:genetics*; D018167:Receptors, Calcitriol / Q000235:genetics*; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic
chemical_list: D005819:Genetic Markers; D018167:Receptors, Calcitriol; D004247:DNA