title: Variations in the vitamin D-binding protein (DBP) gene are related to lower 25-hydroxyvitamin D levels in healthy girls: a cross-sectional study.
abstract: OBJECTIVE
  Vitamin D deficiency has been recognized as a worldwide epidemic affecting several pediatric and adolescent populations. We determined the genotype and haplotype distribution of the rs4588 and rs7041 polymorphisms of the GC gene encoding vitamin D-binding protein (DBP) and investigated the associations between these gene variants and their haplotypes with 25-hydroxyvitamin D [25(OH)D] levels in girls from South Brazil.
  
  
  METHODS
  Cross-sectional study including 198 apparently healthy girls aged 10-18 years. Plasma levels of 25(OH)D were assessed by radioimmunoassay. Participants were genotyped for rs4588 and rs7041 by real-time PCR, with allelic discrimination assays.
  
  
  RESULTS
  Mean chronological age and BMI percentile were 13.17 ± 1.74 years and 57.81 ± 29.03, respectively. Sufficient circulating 25(OH)D levels (≥30 ng/ml) were found in 9.1% of the overall group, insufficient levels (20-29.9 ng/ml) in 59.6%, and deficient levels (<20 ng/ml) in 31.3%. The AA genotype of rs4588, TT genotype of rs7041 and CT-AT/AT-AT (GC 1f-2/2-2) diplotypes were significantly associated with lower 25(OH)D levels, even after adjustment for age and season at the time of blood collection.
  
  
  CONCLUSIONS
  The GC gene genotype may be related to the susceptibility to low 25(OH)D levels in female children and adolescents.
authors.affiliation: Gynecologic Endocrinology Unit, Division of Endocrinology, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil.
authors.forename: Betânia R
authors.initials: BR
authors.lastname: Santos
authors.forename: Luis P G
authors.initials: LP
authors.lastname: Mascarenhas
authors.forename: Margaret C S
authors.initials: MC
authors.lastname: Boguszewski
authors.forename: Poli Mara
authors.initials: PM
authors.lastname: Spritzer
mesh_terms: D000293:Adolescent; D001938:Brazil; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D005838:Genotype; D006801:Humans; D011110:Polymorphism, Genetic; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000235:genetics; D014809:Vitamin D-Binding Protein / Q000097:blood / Q000235:genetics*
chemical_list: D014809:Vitamin D-Binding Protein; D014807:Vitamin D; C104450:25-hydroxyvitamin D