Dataset Information

Vitamin D Binding Protein Impact on 25-Hydroxyvitamin D Levels under Different Physiologic and Pathologic Conditions.

ABSTRACT: There is a high prevalence of vitamin D deficiency worldwide, but how to define vitamin D deficiency is controversial. Currently, the plasma concentration of total 25-hydroxyvitamin D [25(OH)D] is considered an indicator of vitamin D status. The free hormone hypothesis states that protein-bound hormones are inactive while unbound hormones are free to exert biological activity. The majority of circulating 25(OH)D and 1,25(OH)2D is tightly bound to vitamin D binding protein (DBP), 10-15% is bound to albumin, and less than 1% of circulating vitamin D exists in an unbound form. While DBP is relatively stable in most healthy populations, a recent study showed that there are gene polymorphisms associated with race and ethnicity that could alter DBP levels and binding affinity. Furthermore, in some clinical situations, total vitamin D levels are altered and knowing whether DBP is also altered may have treatment implications. The aim of this review is to assess DBP concentration in different physiological and pathophysiological conditions. We suggest that DBP should be considered in the interpretation of 25(OH)D levels.

SUBMITTER: Yousefzadeh P

PROVIDER: S-EPMC4020458 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Vitamin D Binding Protein Impact on 25-Hydroxyvitamin D Levels under Different Physiologic and Pathologic Conditions.

Yousefzadeh Pegah P Shapses Sue A SA Wang Xiangbing X

International journal of endocrinology 20140428

There is a high prevalence of vitamin D deficiency worldwide, but how to define vitamin D deficiency is controversial. Currently, the plasma concentration of total 25-hydroxyvitamin D [25(OH)D] is considered an indicator of vitamin D status. The free hormone hypothesis states that protein-bound hormones are inactive while unbound hormones are free to exert biological activity. The majority of circulating 25(OH)D and 1,25(OH)2D is tightly bound to vitamin D binding protein (DBP), 10-15% is bound ...[more]

PMID: 24868205

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Project description:Circulating 25-hydroxyvitamin D (25-OHD) levels vary among human populations. Only limited information regarding determinants of these measures is available for infants and children, particularly in minority groups at greatest risk for vitamin D deficiency. We identified demographic determinants of circulating 25-OHD in a large cohort of minority children, and now extend our studies to examine potential roles of vitamin D binding protein (DBP) as a determinant of 25-OHD levels. Serum DBP level and common single nucleotide polymorphisms (SNPs) at positions 432 and 436 in the GC gene, encoding DBP, were examined. We confirmed self-reported ancestry using ancestry informative markers (AIMs), and included quantitative AIMs scores in the analysis. The multivariate model incorporated previously identified demographic and nutritional determinants of 25-OHD in this cohort, as well as GC SNPs and circulating DBP. Genetic variants in GC differed by self-reported ancestry. The 1f allele (D432/T436) was enriched in African Americans, occurring in 71%. Homozygosity for the 1f allele (DDTT) occurred in 53% of African Americans but only 6% of Caucasians and 13% of Hispanics. Circulating DBP was significantly correlated with 25-OHD. GC SNPs were associated with both circulating DBP and 25-OHD. It appears that progressive substitution of lysine for threonine at the 436 position results in lower circulating 25-OHD. Multivariate analysis revealed that genetic variance in GC significantly contributes to circulating DBP as well as 25-OHD. Moreover, the effect of GC SNPs on 25-OHD are evident after adjusting for their effects on circulating DBP. Thus in young children genetic variance of the common GC T436K SNP affects circulating levels of the DBP protein, which in turn affects circulating 25-OHD. However, the GC genotype also affects circulating 25-OHD independently of its effect on circulating DBP. These findings provide data that may be important in the interpretation of vitamin D status in children of varying ancestral backgrounds.

Dataset Information

Vitamin D Binding Protein Impact on 25-Hydroxyvitamin D Levels under Different Physiologic and Pathologic Conditions.

Publications

Vitamin D Binding Protein Impact on 25-Hydroxyvitamin D Levels under Different Physiologic and Pathologic Conditions.

Similar Datasets

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