title: Relationship of vitamin D status and bone mass according to vitamin D-binding protein genotypes.
abstract: BACKGROUND
  Vitamin D-binding protein (DBP) may alter the biological activity of total 25-hydroxyvitamin D [25(OH)D]; this could influence on the effects of vitamin D in relation to bone mineral density (BMD) and fractures. Emerging data suggest that fetuin-A may be involved in bone metabolism. We aimed to investigate the influence of DBP gene polymorphism on the relationship of vitamin D status and fetuin-A levels to BMD and bone markers.
  
  
  METHODS
  This cross-sectional study was part of a health survey of employees of the Electricity Generating Authority of Thailand (1,734 healthy subjects, 72% male). Fasting blood samples were assayed for 25(OH)D, fetuin-A, N-terminal propeptides of type 1 procollagen (P1NP), C-terminal cross-linking telopeptides of type I collagen (CTx-I), and DBP rs2282679 genotypes. L1-L4 lumbar spine and femoral BMD were measured using dual-energy X-ray absorptiometry.
  
  
  RESULTS
  The DBP rs2282679 genotype distribution conformed to the Hardy-Weinberg equilibrium. There were no correlations between 25(OH)D levels and BMD and bone markers. But a trend of positive correlation was observed for the DBP genotypes with total hip BMD, and for the interaction between 25(OH)D and DBP genotypes with BMD at all femoral sites. We further analyzed data according to DBP genotypes. Only in subjects with the AA (common) genotype, 25(OH)D levels were positively related to BMD and bone markers, while fetuin-A was negatively related to total hip BMD, independently of age, gender and BMI.
  
  
  CONCLUSIONS
  The interaction between vitamin D status, as measured by circulating 25(OH)D and DBP rs2282679 genotypes, modified the association between 25(OH)D and BMD and bone markers. Differences in DBP genotypes additionally influenced the correlation of fetuin-A levels with femoral BMD.
authors.affiliation: Department of Medicine and Research Center, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Rama VI Road, Ratchathewi, Bangkok, 10400, Thailand. hataikarnn@hotmail.com.
authors.forename: Hataikarn
authors.initials: H
authors.lastname: Nimitphong
authors.affiliation: Department of Radiology, Ramathibodi Hospital, Mahidol University, Rama VI Road, Ratchathewi, Bangkok, 10400, Thailand. chanika.sri@mahidol.ac.th.
authors.forename: Chanika
authors.initials: C
authors.lastname: Sritara
authors.affiliation: Department of Medicine and Research Center, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Rama VI Road, Ratchathewi, Bangkok, 10400, Thailand. laor.cha@mahidol.ac.th.
authors.forename: La-Or
authors.initials: LO
authors.lastname: Chailurkit
authors.affiliation: Department of Medicine and Research Center, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Rama VI Road, Ratchathewi, Bangkok, 10400, Thailand. suwannee.cha@mahidol.ac.th.
authors.forename: Suwannee
authors.initials: S
authors.lastname: Chanprasertyothin
authors.affiliation: Health Office, Electricity Generating Authority of Thailand, Nonthaburi, 11130, Thailand. wiparatanac@gmail.com.
authors.forename: Wipa
authors.initials: W
authors.lastname: Ratanachaiwong
authors.affiliation: Department of Medicine and Research Center, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Rama VI Road, Ratchathewi, Bangkok, 10400, Thailand. piyamitr.sri@mahidol.ac.th.
authors.forename: Piyamitr
authors.initials: P
authors.lastname: Sritara
authors.affiliation: Department of Medicine and Research Center, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Rama VI Road, Ratchathewi, Bangkok, 10400, Thailand. boonsong.ong@mahidol.ac.th.
authors.forename: Boonsong
authors.initials: B
authors.lastname: Ongphiphadhanakul
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods; D000328:Adult; D015415:Biomarkers / Q000097:blood; D015519:Bone Density / Q000235:genetics* / Q000502:physiology; D002112:Calcifediol / Q000097:blood* / Q000378:metabolism; D024042:Collagen Type I / Q000097:blood; D003430:Cross-Sectional Studies; D004268:DNA-Binding Proteins; D005215:Fasting / Q000097:blood; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging; D005838:Genotype; D006615:Hip / Q000000981:diagnostic imaging; D006801:Humans; D008161:Lumbosacral Region / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments / Q000097:blood; D010455:Peptides / Q000097:blood; D011347:Procollagen / Q000097:blood; D013223:Statistics as Topic; D014157:Transcription Factors; D014807:Vitamin D / Q000097:blood* / Q000378:metabolism; D014809:Vitamin D-Binding Protein / Q000235:genetics*; D060749:alpha-2-HS-Glycoprotein / Q000032:analysis
chemical_list: D015415:Biomarkers; D024042:Collagen Type I; C063898:DBP protein, human; D004268:DNA-Binding Proteins; D010446:Peptide Fragments; D010455:Peptides; D011347:Procollagen; D014157:Transcription Factors; D014809:Vitamin D-Binding Protein; D060749:alpha-2-HS-Glycoprotein; C052929:collagen type I trimeric cross-linked peptide; C047202:procollagen Type I N-terminal peptide; D014807:Vitamin D; D002112:Calcifediol