title: Vitamin D binding protein gene polymorphism as a risk factor for vitamin D deficiency in Thais.
abstract: OBJECTIVE
  Vitamin D deficiency is related to increased risks for a number of diseases. To date, at least 3 candidate genes, vitamin D binding protein (VDBP) gene (GC), 25-hydroxylase (CYP2R1), and 7-dehydrocholesterol reductase/NAD synthetase 1 (DHCR7/NADSYN1), have been associated with serum 25-hydroxyvitamin D (25[OH]D) levels, but their influences on the prevalence of vitamin D deficiency in relation to other known risk factors have not been clearly defined.
  
  
  METHODS
  The study assessed 4,476 individuals aged 14 to 93 years from the Thailand 4th National Health Examination Survey (2008-2009) and the Electricity Generating Authority of Thailand (EGAT) (2008) cohorts. The GC rs2282679 polymorphism on chromosome 4q12-q13 was genotyped by real-time polymerase chain reaction (PCR). Serum 25(OH)D was measured by liquid chromatography/tandem mass spectrometry. Vitamin D deficiency was defined as a 25(OH)D concentration <20 ng/mL.
  
  
  RESULTS
  Data were expressed as mean ± SD. There were 2,747 (61.4%) males and 1,729 (38.6%) females in the study, with an average body mass index (BMI) of 23.7 ± 4.2 kg/m2 and a mean total 25(OH)D of 28.9 ± 9.0 ng/mL. Serum 25(OH)D levels decreased progressively with the presence of the C allele. Using multiple logistic regression analysis, vitamin D deficiency was significantly associated with the GC rs2282679 genotype (odds ratio [OR] per C allele 1.80, 95% confidence interval CI 1.57-2.01), independent of established risk factors for vitamin D deficiency including age, sex, and BMI.
  
  
  CONCLUSIONS
  A specific GC gene polymorphism is associated with lower 25(OH)D levels independent of age, sex, and adiposity in Thai subjects.
authors.affiliation: Department of Medicine, Mahidol University, Bangkok 10400, Thailand.
authors.forename: Pranee
authors.initials: P
authors.lastname: Thongthai
authors.affiliation: Department of Medicine, Mahidol University, Bangkok 10400, Thailand.
authors.forename: La-or
authors.initials: LO
authors.lastname: Chailurkit
authors.affiliation: Research Center, Mahidol University, Bangkok 10400, Thailand.
authors.forename: Suwannee
authors.initials: S
authors.lastname: Chanprasertyothin
authors.affiliation: Department of Medicine, Mahidol University, Bangkok 10400, Thailand.
authors.forename: Hataikarn
authors.initials: H
authors.lastname: Nimitphong
authors.affiliation: Department of Medicine, Mahidol University, Bangkok 10400, Thailand.
authors.forename: Piyamitr
authors.initials: P
authors.lastname: Sritara
authors.affiliation: Department of Community Medicine, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok 10400, Thailand.
authors.forename: Wichai
authors.initials: W
authors.lastname: Aekplakorn
authors.affiliation: Department of Medicine, Mahidol University, Bangkok 10400, Thailand.
authors.forename: Boonsong
authors.initials: B
authors.lastname: Ongphiphadhanakul
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People / Q000235:genetics*; D005260:Female; D005838:Genotype; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D012307:Risk Factors; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000209:etiology / Q000235:genetics*; D014809:Vitamin D-Binding Protein / Q000235:genetics*
chemical_list: D014809:Vitamin D-Binding Protein; D014807:Vitamin D; C104450:25-hydroxyvitamin D