•Vitamin D deficiency is common in the Middle East.•Response to Vitamin D supplementation is genetically influenced.•SNPs in GC gene can predict response to vitamin D supplementation.•Carriers of ...rs4588/rs7041 in GC had lowest response to vitamin D supplementation.
The aim of this study was to determine the influence of vitamin D–binding protein (DBP) gene polymorphisms in vitamin D metabolites before and after vitamin D supplementation.
In all, 234 participants (126 women; 108 men) with vitamin D deficiency 25(OH)D <50 nmol/L were given 50 000 IU of vitamin D supplements for 8 wk followed by daily maintenance of 1000 IU for 4 mo. Two single-nucleotide polymorphisms (rs4588 and rs7041) in DBP coding gene were assessed.
Baseline 25(OH)D was significantly in higher in participants with homozygous major genotype of rs7041 than other genotypes (P = 0.02). Postsupplementation 25(OH)D was significantly higher in participants with homozygous major genotypes of either rs4588 and rs7041 than other genotypes (P < 0.001). Participants with the minor allele of either rs4588 or rs7041 were 2.9 (1.9–4.5) times and 3.7 (2.1–6.6) times, respectively, more likely to be non-responders (postsupplementation 25 OHD <50 nmol/L) than those homozygous for the major allele at these locations (P < 0.001). Furthermore, participants with homozygous minor and heterozygous genotype of rs7041 were 6.2 and 4.2times more likely to be non-responders than those with the homozygous major genotype (P < 0.001) even after adjustments for age, sex, body mass index, baseline 25(OH)D concentration, and other alleles. Participants with homozygous minor and heterozygous genotypes of rs4588 were 4.1 and 12.4times more likely to be non-responders than those with homozygous major genotypes. These significant risks, however, were lost after adjustment.
rs7041 and rs4588 variants of the DBP gene are associated with variations in 25(OH)D levels and efficacy of response to vitamin D supplementation in Saudi Arabian adults.
The study aimed to determine the influence of DBP gene polymorphisms in vitamin D metabolites before and after vitamin D supplementation. Out of 234 participants (126 females and 108 males), 146 had ...vitamin D deficiency (25(OH)D <50nmol/l) and were given 2000IU daily dose of vitamin D for 12 months. Two common single nucleotide polymorphisms (SNPs), (rs4588 and rs7041) of the
DBP
gene were assessed. Post supplementation median 25(OH)D was significantly higher 61.2 (46.3-76.8) and 66.6 (53.2-83.7) in participants with CC genotype of rs4588 and GG genotype of rs7041 than other genotypes (p<0.001). Participants with T allele are 2.9 (1.9-4.5) times more likely to be a non-responder (unable to achieve serum 25(OH)D post-supplementation) than those with G allele (p<0.001). Participants with A allele are 3.7 (2.1-6.6) times more likely to be a non-responder than those with C allele (p<0.001). Furthermore, participants with TT and TG are 6.2 and 4.2 times more likely to be a non-responder than those with the GG genotype (p-values <0.001) even after adjustments for age, gender, BMI, baseline 25(OH)D concentration and other alleles. Participants with AA and CA genotypes are 12.4 (1.4-110) and 4.1 (2.1-8.0) times more likely to be non-responders as compared to those with CC genotype but lost significance after adjustment. The SNPs, rs7041 and rs4588 variants of the
DBP
gene are associated with baseline 25(OH)D levels and modifies 25(OH)D response after vitamin D supplementation in Saudi adults.
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