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ContextSingle nucleotide polymorphisms (SNPs) of the vitamin D binding protein encoding the GC (group component) gene affect 25-hydroxyvitamin D (25OHD) concentrations, but their influence on vitamin D status and response to vitamin D supplementation in infants is unknown.ObjectiveTo study GC genotype–related differences in 25OHD concentrations and the response to supplementation during a vitamin D intervention study in infants.DesignIn this randomized controlled trial, healthy term infants received vitamin D3 (10 or 30 μg/d) from 2 weeks to 24 months of age. GC SNPs rs2282679, rs4588, rs7041, and rs1155563 were genotyped. rs4588/7041 diplotype and haplotypes of rs2282679, rs4588, and rs7041 (Haplo3SNP) and of all four SNPs (Haplo4SNP) were determined.Main Outcome Measures25OHD measured in cord blood at birth and at 12 and 24 months during intervention.ResultsA total of 913 infants were included. Minor allele homozygosity of all studied GC SNPs, their combined haplotypes, and rs4588/rs7041 diplotype 2/2 were associated with lower 25OHD concentrations at all time points in one or both intervention groups [analysis of covariance (ANCOVA) P < 0.043], with the exception of rs7041, which did not affect 25OHD at birth. In the high-dose supplementation group receiving 30 μg/d vitamin D3, but not in those receiving 10 µg/d, genotype of rs2282679, rs4588, and rs7041; diplotype; and Haplo3SNP significantly affected intervention response (repeated measurement ANCOVA Pinteraction < 0.019). Minor allele homozygotes had lower 25OHD concentrations and smaller increases in 25OHD throughout the intervention.ConclusionsIn infants, vitamin D binding protein genotype affects 25OHD concentration and efficiency of high-dose vitamin D3 supplementation.

Context The relationship of maternal and infant 25-hydroxyvitamin D concentration [25(OH)D] with infant growth is unclear. Objective Our objective was to explore whether 25(OH)D in pregnancy, umbilical cord blood (UCB), or in infancy was associated with infant growth. Design This study involved 798 healthy infants and their mothers in Finland. We assessed 25(OH)D during pregnancy, from UCB at birth, and from the infant at the age of 12 months. Main Outcome Measures Infant length, weight, length-adjusted weight, and head circumference at 6 and 12 months and midupper-arm circumference at 12 months. Results Of the mothers and infants, 96% and 99% were vitamin D sufficient [25(OH)D ≥50 nmol/L], respectively. Mothers with pregnancy 25(OH)D >125 nmol/L had the shortest, lightest (in weight), and thinnest (in length-adjusted weight) infants at 6 months (P for all < 0.05). For each 10 nmol/L higher UCB 25(OH)D, the infants were 0.03 SD score (SDS) shorter at 6 months (95% CI −0.05 to −0.01), adjusted for birth size, infant 25(OH)D, and parental height. Higher UCB 25(OH)D associated with smaller head circumference at 6 and 12 months (P for all 125 nmol/L had the thinnest infants at 12 months (P = 0.021). For each 10 nmol/L higher infant 25(OH)D, the infants were 0.03 SDS lighter (−0.05 to −0.01) and 0.03 SDS thinner (−0.05 to 0.00) at 12 months. Conclusions Our results suggest that high pregnancy, cord blood, and infant vitamin D concentration may have disadvantageous effects on infant growth.

Context: Vitamin D deficiency is common in renal transplant recipients (RTR). The long-term implications of vitamin D deficiency in RTR remain unclear.Objective: We investigated whether 25(OH) or 1,25(OH)(2) vitamin D levels are associated with mortality, renal function decline, and graft failure in stable RTR.Design: Observational study with longitudinal design. Followup was 7.0, interquartile range (IQR) 6.2-7.5 years.Setting: Single-center outpatient clinic.Participants: 435 stable RTR (51% men, mean age 52 +/- 12 years) were included at a median [IQR] of 6 [3-12] years after kidney transplantation.Main Outcome Measures: All-cause mortality, annual change of estimated glomerular filtration rate (eGFR), and graft failure.Results: Mean 25-hydroxyvitamin D [25(OH)D] and 1,25-dihydroxyvitamin D [1,25(OH)(2)D] were 21.6 +/- 9.1 ng/ml and 45.2 +/- 19.0 pg/ml, respectively. During followup, 99 patients (22.8%) died and 44 patients (10.1%) developed graft failure. In univariable analysis, both 25(OH)D and 1,25(OH)(2)D were significantly associated with mortality (hazard ratio [HR], 0.64; 95% confidence interval (CI), 0.51-0.81; P Conclusions: Low 25(OH) D is independently associated with an increased risk of all-cause mortality and 25(OH) D