Genetic and environmental determinants of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D levels in Hispanic and African Americans

J Clin Endocrinol Metab. 2008 Sep;93(9):3381-8. doi: 10.1210/jc.2007-2702. Epub 2008 Jul 1.

Abstract

Context: Vitamin D deficiency is associated with many adverse health outcomes, yet little is known about the genetic epidemiology of vitamin D or its metabolites.

Objective: Our objective was to examine the relationship among three vitamin D-related genes and levels of 25-hydroxyvitamin D [25(OH)D] and 1,25-dihydroxyvitamin D [1,25(OH)2D] in Hispanics (HAs) and African Americans (AAs).

Design and setting: The cross-sectional Insulin Resistance Atherosclerosis Family Study recruited and examined subjects in: Los Angeles, California (AAs; 513 individuals from 42 families); San Luis Valley (SLV), Colorado (HAs; 513 individuals from 30 families); and San Antonio (SA), Texas (HAs; 504 individuals from 58 families).

Main outcome measures: Plasma levels of 25(OH)D and 1,25(OH)2D were measured.

Results: Levels of 25(OH)D were highest in SLV-HAs [18.3 +/- 7.7 ng/ml (45.7 +/- 19.2 nmol/liter)], lower in SA-HAs [14.6 +/- 6.4 ng/ml (36.4 +/- 16.0 nmol/liter)], and lowest in AAs [11.0 +/- 5.4 ng/ml (27.5 +/- 13.5 nmol/liter)]. Levels of 1,25(OH)2D were similar in AAs [43.5 +/- 13.9 pg/ml (113.1 +/- 36.1 pmol/liter)] and SLV-HAs [43.2 +/- 13.3 pg/ml (112.3 +/- 34.6 pmol/liter)], but higher in SA-HAs [48.6 +/- 17.0 pg/ml (126.4 +/- 44.2 pmol/liter)]. After adjusting for gender and age within the site, two single nucleotide polymorphisms (SNPs) in the vitamin D binding protein gene (DBP), rs4588 and rs7041, were associated with 25(OH)D, and one SNP in the DBP, rs4588, was associated with 1,25(OH)2D at all three study centers.

Conclusions: SNPs in the DBP are associated with levels of 25(OH)D and 1,25(OH)2D in HA and AA participants in the Insulin Resistance Atherosclerosis Family Study.

Publication types

  • Multicenter Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • 25-Hydroxyvitamin D3 1-alpha-Hydroxylase / genetics
  • Adolescent
  • Adult
  • African Americans / genetics*
  • Calcitriol / blood*
  • Calcitriol / genetics
  • Cross-Sectional Studies
  • Female
  • Hispanic Americans / genetics*
  • Humans
  • Linkage Disequilibrium
  • Male
  • Middle Aged
  • Polymorphism, Single Nucleotide
  • Receptors, Calcitriol / genetics
  • Vitamin D / analogs & derivatives*
  • Vitamin D / blood
  • Vitamin D / genetics
  • Vitamin D Deficiency / blood
  • Vitamin D Deficiency / ethnology*
  • Vitamin D Deficiency / genetics*
  • Vitamin D-Binding Protein / genetics

Substances

  • Receptors, Calcitriol
  • Vitamin D-Binding Protein
  • Vitamin D
  • 25-hydroxyvitamin D
  • 25-Hydroxyvitamin D3 1-alpha-Hydroxylase
  • Calcitriol