GC Single Nucleotide Polymorphisms Research Articles

Relation of T Cell Profile with Vitamin D Receptor and Vitamin D-Binding Protein Gene Polymorphisms in Atopy.

Atopic diseases, including atopic dermatitis (AD) and allergic asthma (AA), are characterized by complex immune responses involving various T cells subsets and their cytokine profiles. It is assumed that single nucleotide polymorphisms (SNPs) in the Vitamin D receptor (VDR) gene and the Vitamin D-binding protein (GC) gene are related to the action of Vitamin D and, consequently, play a role in regulating the immune response. However, there is not enough data to unequivocally support the hypothesis about the relationship between T cells profile and VDR or GC SNPs. Two hundred sixty-six subjects (aged > 18 years) were involved in the study: 100 patients with mild or moderate AD, 85 patients with mild or moderate AA, and 81 healthy individuals. Blood cell counts were determined by standard methods. Flow cytometric analysis was used to evaluate CD4+ T-helper (Th) cell subtypes: Th2, Th1, Th17, and T regulatory (Treg) cells in peripheral blood. Measurements of cytokines, total immunoglobulin E (IgE), and Vitamin D levels in serum were evaluated by ELISA. Significantly higher levels of Th1, Th2, and Th17 cells, along with lower levels of Tregs, were found in patients with atopic diseases compared to healthy individuals. Additionally, higher serum levels of interleukin (IL) 5, IL-17A, and transforming growth factor-β1 (TGF-β1), as well as lower levels of IL-10, were observed in patients with atopic diseases than in control. The study established associations between VDR SNPs and immune profiles: the AA genotype of rs731236 was associated with increased Th2 and Th17 cells and a higher Th1/Th2 ratio; the GG genotype of rs731236 was linked to decreased serum IL-10 and TGF-β1 levels; and the TT genotype of rs11168293 was associated with increased IL-10 levels. Additionally, the GG genotype of GC gene SNP rs4588 was associated with reduced Th2 and Th17 lymphocytes, while the TT genotype of rs4588 was linked to decreased IL-10 levels. Furthermore, the CC genotype of rs7041 was associated with higher levels of Th2, Th17, IL-10, and IL-35, as well as reduced levels of TGF-β1, while the GG genotype of rs3733359 was associated with reduced IL-10 levels. In conclusion, our study demonstrates that the Vitamin D receptor gene single nucleotide polymorphisms rs731236 and rs11168293, along with polymorphisms in the Vitamin D-binding protein gene (rs4588, rs7041, rs3733359), are significantly associated with variations in T cell profiles in atopy. These variations may play a crucial role in promoting inflammation and provide insight into the genetic factors contributing to the pathogenesis of atopy.

Single nucleotide polymorphisms in vitamin D binding protein and 25-hydroxylase genes affect vitamin D levels in adolescents of Arab ethnicity in Kuwait.

Vitamin D deficiency (VDD) is widespread in the Arab world despite ample sunshine throughout the year. In our previous study, lifestyle and socio-demographic factors could explain only 45% of variability in vitamin D levels in Kuwaiti adolescents, suggesting that genetics might contribute to VDD in this region. Single nucleotide polymorphisms (SNP) in the 25-hydroxylase (CYP2R1) and the GC globulin (GC) genes have been reported to affect vitamin D levels in various ethnic groups in adults. In this study, we investigated the association of two SNPs from GC (rs4588 and rs7041) and three SNPs from CYP2R1 (rs10741657, rs11023374 and rs12794714) with vitamin D levels and VDD in a nationally representative sample of adolescents of Arab ethnicity from Kuwait. Multivariable linear regression, corrected for age, sex, parental education, governorate, body mass index, and exposure to sun, demonstrated that each of the 5 study variants showed significant associations with plasma 25(OH)D levels in one or more of the additive, recessive, and dominant genetic models - the rs10741657 under all the three models, rs12794714 under both the additive and recessive models, rs7041 under the recessive model; and rs4588 and rs11023374 under the dominant model. Minor alleles at rs4588 (T), rs7041 (A), rs11023374 (C), and rs12794714 (A) led to a decrease in plasma 25(OH)D levels - rs4588:[β (95%CI) = -4.522 (-8.66,-0.38); p=0.033]; rs7041:[β (95%CI) = -6.139 (-11.12,-1.15); p=0.016]; rs11023374:[β (95%CI) = -4.296 (-8.18,-0.40); p=0.031]; and rs12794714:[β (95%CI) = -3.498 (-6.27,-0.72); p=0.014]. Minor allele A at rs10741657 was associated with higher levels of plasma 25(OH)D levels [β (95%CI) = 4.844 (1.62,8.06); p=0.003)] and lower odds of vitamin D deficiency (OR 0.40; p=0.002). These results suggest that the CYP2R1 and GC SNP variants are partly responsible for the high prevalence of VDD in Kuwait. Genotyping these variants may be considered for the prognosis of VDD in Kuwait.

Association of SNPs in GC and CYP2R1 with total and directly measured free 25-hydroxyvitamin D in multi-ethnic postmenopausal women in Saudi Arabia.

BackgroundGroup-specific component (GC) and cytochrome P450 Family 2 Subfamily R Member 1 (CYP2R1) genes are one of the vital genes involved in the vitamin D (vitD) metabolic pathway. Association of genetic polymorphisms in these two genes with 25-hyroxyvitamin D (25(OH)D) level has been reported in several studies. However, this association has been reported to be discrepant among populations from different ethnicities. Therefore, we aimed in this study to investigate association of the two major single nucleotide polymorphisms (SNP) in GC (rs4588 and rs7014) and a SNP (rs12794714) in CYP2R1 in postmenopausal women in Saudi Arabia.MethodsThis study randomly selected 459 postmenopausal women (aged ≥50 years) of multiple ethnicities in Jeddah, Saudi Arabia. Blood samples were collected from all participating women for DNA extraction and for assessment of serum levels of total 25(OH)D, directly measured free 25(OH)D and other biochemical parameters. SNPs in selected vitD related genes (rs4588 in GC, c.1364G > T with transcript ID: NM_001204307.1 and rs7041 in GC, c.1353A > C with transcript ID NM_001204307.1 and rs12794714 in CYP2R1, c.177G > A with transcript ID NM_024514.4) were determined in DNA samples using Sanger DNA sequencing.ResultsMinor allele frequency for rs4588, rs7041 and rs12794714 were 0.25, 0.44 and 0.42 respectively. Genotypes of rs7041 showed significant difference in total 25(OH)D level but not in free 25(O)D level (P = 0.023). In comparison, genotypes of rs4588 and rs12794714 did not show any significant difference neither in total nor in free 25(OH)D level. Post hoc test revealed that total 25(OH)D was lower in the rs7041 TT allele compared to the GG allele (P = 0.022). Chi-square test showed that vitD status was associated with rs7041 genotypes (P = 0.035). In addition, rs7041 minor alleles were found to have an association with vitD deficiency with a statistical significant odds ratio (>1) of 2.24 and 3.51 with P = 0.006 and P = 0.007 for TG and GG genotypes respectively.ConclusionThe rs7041 SNP in GC was associated with total 25(OH)D level in postmenopausal women in Saudi Arabia, while rs4588 in GC and rs12794714 in CYP2R1 did not show association with total 25(OH)D. Further studies exploring additional variants in vitD related genes are needed to understand genetic factors underlying vitD deficiency in Saudi population.

Association of vitamin D pathway genes polymorphisms with pulmonary tuberculosis susceptibility in a Chinese population

ObjectiveThis study aimed to evaluate the association of single nucleotide polymorphisms (SNPs) of vitamin D metabolic pathway genes with susceptibility to pulmonary tuberculosis (PTB).MethodsNine hundred seventy-nine patients (490 PTB cases and 489 healthy controls) were included in this study. Seventeen SNPs of vitamin D metabolic pathway genes, including CYP24A1, CYP27A1, CYP27B1, CYP2R1, GC, and DHCR7, were genotyped with improved multiple ligase detection reaction (iMLDR).ResultsThe GC rs3733359 GA, rs16847024 CT genotypes were significantly associated with the reduced risk of PTB, and the rs3733359 A, rs16847024 T alleles were also associated with the decreased PTB susceptibility. The GT genotype of GC rs4588 variant was significantly higher in patients with PTB when compared to controls. Moreover, the increased risk of rs3733359 and rs16847024 variants, and a decreased risk of rs4588, were found under the dominant mode among the PTB patients. However, there was no significant relationship of CYP24A1, CYP27A1, CYP27B1, CYP2R1, and DHCR7 polymorphisms with the risk of PTB. In CYP27A1, the rs17470271 T and rs933994 T alleles were significantly associated with leukopenia, drug resistance in the PTB patients, respectively. In GC gene, the rs7041 and rs3733359 variants were found to be associated with pulmonary infection, fever in the PTB patients, respectively. The increased frequency of rs16847024 TT genotype was found in the PTB patients with fever and drug-induced liver damage. DHCR7 rs12785878 TT genotype, and T allele frequencies were both significantly associated with pulmonary infection in the PTB patients. The haplotype analysis showed that CYP24A1 TACT, CYP2R1 GGCT, GGAT, GC AATG haplotypes were related to PTB susceptibility.ConclusionOur study suggested that GC SNPs were associated with the genetic background of PTB. CYP27A1, GC, and DHCR7 genetic variations might contribute to several clinical phenotypes of PTB in Chinese.

Association of Vitamin D Receptor and Vitamin D-Binding Protein Polymorphisms with Familial Breast Cancer Prognosis in a Mono-Institutional Cohort.

Low 25-hydroxyvitamin D (25OHD) has been associated with an increased cancer incidence and poorer prognosis. Single nucleotide polymorphisms (SNPs) of vitamin D receptor (VDR) and vitamin D binding protein (GC gene) may interfere with vitamin D activity. This study assesses the role of VDR and GC SNPs on breast cancer (BC) recurrence and survival in a cohort of patients with a family history of breast cancer, without the pathogenic variant for BRCA1 and BRCA2. A consecutive series of patients who underwent genetic testing were genotyped for VDR and GC genes. Specifically, ApaI, FokI, TaqI, BsmI and rs2282679, rs4588, rs7041 SNPs were determined. A total of 368 wild type (WT) patients with BC were analyzed for VDR and GC SNPs. The GC rs2282679 minor allele was significantly associated with luminal subtype of the primary tumor compared to Her2+/TN breast cancer (p = 0.007). Multivariate Cox models showed that BmsI and TaqI are significantly associated with BC outcome. Patients with the major alleles showed more than 30% lower hazard of relapse (BsmI p = 0.02 and TaqI p = 0.03). Our study supports the evidence for a pivotal role of 25OHD metabolism in BC. GC SNPs may influence the hormone tumor responsiveness and VDR may affect tumor prognosis.

Association of Vitamin D Metabolism Gene Polymorphisms with Autoimmunity: Evidence in Population Genetic Studies.

A high prevalence of vitamin D (calcidiol) serum deficiency has been described in several autoimmune diseases, including multiple sclerosis (MS), rheumatoid arthritis (AR), and systemic lupus erythematosus (SLE). Vitamin D is a potent immunonutrient that through its main metabolite calcitriol, regulates the immunomodulation of macrophages, dendritic cells, T and B lymphocytes, which express the vitamin D receptor (VDR), and they produce and respond to calcitriol. Genetic association studies have shown that up to 65% of vitamin D serum variance may be explained due to genetic background. The 90% of genetic variability takes place in the form of single nucleotide polymorphisms (SNPs), and SNPs in genes related to vitamin D metabolism have been linked to influence the calcidiol serum levels, such as in the vitamin D binding protein (VDBP; rs2282679 GC), 25-hydroxylase (rs10751657 CYP2R1), 1α-hydroxylase (rs10877012, CYP27B1) and the vitamin D receptor (FokI (rs2228570), BsmI (rs1544410), ApaI (rs7975232), and TaqI (rs731236) VDR). Therefore, the aim of this comprehensive literature review was to discuss the current findings of functional SNPs in GC, CYP2R1, CYP27B1, and VDR associated to genetic risk, and the most common clinical features of MS, RA, and SLE.

Influence of vitamin D binding protein polymorphism, demographics and lifestyle factors on vitamin D status of healthy Malaysian pregnant women

BackgroundVitamin D deficiency (VDD) has been related to vitamin D binding protein (GC) gene polymorphism, demographics and lifestyle factors in different populations. However, previous studies only focused on demographic and lifestyle factors or genetic factors alone. Therefore, this cross-sectional study aimed to assess the association between GC gene polymorphism, demographics and lifestyle factors with VDD among Malaysian pregnant women.MethodInformation on demographic characteristics, dietary vitamin D intake from supplement and food, time spent outdoors, skin type and clothing were collected using a questionnaire. Plasma total 25-hydroxyvitamin D (25OHD) levels were measured using an Ultra-High-Performance Liquid Chromatography (UHPLC). Maternal GC single nucleotide polymorphisms (SNPs) (rs4588 and rs7041) were determined using restriction fragment length polymorphism (RFLP) technique.ResultsResults showed that 50.2% of pregnant women were vitamin D deficient (25OHD < 30 nmol/L). VDD (25OHD < 30 nmol/L) was significantly associated with age, veiled clothing, maternal vitamin D intakes from both food and supplements, and GC rs7041(and GC diplotypes). In contrast to previous studies that reported for non-pregnant population, a significant positive association was found between CC genotype for SNP GC rs7041, GC 1s–1s and GC If-2 with risk of VDD (25OHD < 30 nmol/L).ConclusionsThe high prevalence of maternal VDD found in this study suggests the need for urgent development and implementation of vitamin D supplementation or fortification strategies to reduce VDD among pregnant women. The discrepancy in the association between GC rs7041 gene polymorphism and VDD reflects the variation in the factors associated with VDD in pregnancy compared to non-pregnant state.

Abstract 247: Molecular markers of the vitamin D pathway and esophageal adenocarcinoma survival

Abstract We investigated the potential prognostic association between vitamin D levels (25-Hydroxyvitamin D [25(OH)D]) and vitamin D pathway single nucleotide polymorphisms (SNPs) with overall survival (OS) in esophageal adenocarcinoma (EA) patients. EA patients were recruited from Massachusetts General Hospital near the time of their diagnosis between 1999 and 2016. At the time of recruitment, patients completed a baseline questionnaire and provided blood and serum samples. Serum 25(OH)D levels were measured using radioimmunoassay and adjusted for month of blood draw. Genotypes for 48 tag SNPs from seven candidate genes in the vitamin D pathway (GC, CYP2R1, CYP27A1, CYP27B1, CYP24A1, VDR and RXRA) were determined from whole blood DNA. For survival outcomes, we used log-rank test and a multivariable extended Cox model to estimate adjusted hazard ratio (HR) of death. HR models for each SNP were restricted to patients who identified as White and adjusted for age, sex, smoking status, diagnosis year, and treatment, stratifying baseline hazard by clinical stage and modeling surgical resection as a time-dependent covariate. HR models by quartiles 25(OH)D, additionally adjusted for body mass index (BMI), and timing of blood draw. Our analyses included EA patients with complete information on relevant confounders and predictors of OS. The 25(OH)D analysis included 463 EA patients and 337 deaths, with median follow-up of 23.1 months. The mean 25(OH)D level at diagnosis was 20.7 ng/mL. We found no evidence that OS curves differed across quartiles of vitamin D (log rank p=0.83). In the adjusted extended cox model, we found no difference in OS among the highest quartile and quartiles 2-4 (respectively, HR (95% confidence interval), 0.95 (0.70, 1.31), 1.03 (0.76,1.39), 1.01 (0.73, 1.38), global p=0.97). We did not find evidence of interaction between 25(OH)D and clinical stage (p=0.88) or BMI (p=0.43) on OS, and this relationship did not differ by timing of blood draw. Preliminary SNP analysis included 424 EA patients and 305 deaths, with median follow-up of 24.1 months. Two SNPs in CYP24A1 (SNP, HR (95% confidence interval) per minor allele: rs1570669, 1.23 (1.04-1.45); rs927650, 1.22 (1.04-1.44)), two SNPs in GC (rs4588, 1.25(1.04-1.49); rs7041, 0.84(0.71-0.99)), and one SNP in RXRA (rs7039190, 1.57(1.06, 2.31)) were marginally associated with OS in the multivariable survival model. SNPs were not statistically significant after adjusting p-value for multiple testing. Based on the available evidence from our analyses, markers in the vitamin D pathway at the time of diagnosis are not clinically relevant markers of EA survival. Citation Format: Elizabeth Loehrer, Rebecca Betensky, Ruyang Zhang, Li Su, Edward Giovannucci, David Christiani. Molecular markers of the vitamin D pathway and esophageal adenocarcinoma survival [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 247.

Effects of maternal genetic polymorphisms in vitamin D-binding protein and serum 25-hydroxyvitamin D concentration on infant birth weight

ObjectiveVitamin D deficiency is a common problem during pregnancy and might contribute to adverse birth outcomes. Vitamin D-binding protein plays a key role in regulating vitamin D metabolism. We investigated whether maternal genetic variation in GC, the gene encoding vitamin-D binding protein, modulates the relationship between 25-hydroxyvitamin D [25(OH)D] levels and infant birth weight. MethodsWe measured 25(OH)D concentrations in maternal and umbilical cord blood from 356 pregnant women and their infants by liquid chromatography tandem mass spectrometry. We extracted DNA from the maternal blood for genotyping GC single-nucleotide polymorphisms (SNPs). ResultsThe 25(OH)D concentrations were significantly higher in the maternal blood than in the cord blood, although the concentrations from each source were positively correlated with one another among individuals. Maternal GC SNPs rs12512631 and rs7041 were not significantly associated with infant birth weight. On the other hand, the GC SNPs rs12512631 and rs7041 significantly modified the relationships between the maternal and cord-blood concentrations of 25(OH)D and birth weight. Low 25(OH)D levels in the maternal and cord blood were significantly associated with decreased birth weight among infants born to mothers carrying the rs12512631 ‘C’ allele but not in those born to mothers homozygous for the ‘T’ allele (P-interaction = 0.043 and 0.0008 for the maternal and cord blood, respectively). Low 25(OH)D levels in the cord blood were significantly associated with decreased birth weight only among infants born to mothers carrying the rs7041 ‘G’ allele (P-interaction = 0.009). ConclusionsOur findings suggest that the interaction between 25(OH)D status and some maternal GC variants influence the birth weight of infants.

Abstract 1909: Associations of Vitamin D related polymorphisms with hereditary breast cancer in 1025 subjects undergoing BRCA 1/2 testing

Abstract Background: Vitamin D plays an important role in many normal body functions, including regulation of cell growth, bone formation, inflammation, neuromuscular and immune function. Lower serum levels of 25-hydroxyvitamin D, an index of vitamin D status, are associated with greater risk of cancer. Genetic variants in vitamin D related genes have been linked to breast cancer (BC) risk. These include the vitamin D receptor (VDR) and the GC gene that encodes for the vitamin D binding protein. Aims: To determinate the frequency of 5 single nucleotide polymorphisms (SNPs) of VDR and GC in a large cohort of subjects candidate to BRCA 1/2 genetic testing and to assess any interaction between vitamin D and BRCA pathways on disease outcome. Methods: From 2002 to 2012 blood samples from 1025 subjects with family history of ovarian cancer (OC) or BC were collected after informed consent was signed during the genetic counseling. DNA was extracted from whole EDTA treated blood and Allelic Discrimination (Applied Biosystems’ Taqman assays) of VDR (BsmI, FokI, TaqI, ApaI) and GC SNPs is ongoing. Results: At last follow-up in February 2014 our cohort included 272 unaffected subjects (117 BRCA carriers, 37 WT and 118 true negative) and 753 affected subjects (276 BRCA1/2 carriers, 469 WT and 1 true negative subjects). Amongst BC patients (N = 675), 221 were BRCA carriers, 446 WT, and 8 true negative. Those affected ofBC and OC (N = 27), included 23 BRCA carriers and 4 WT, while OC patients (N = 51) included 32 BRCA carriers and 19 WT. Here we present the preliminary data obtained for VDR and GC SNPs in 833 and 710 subjects, respectively. None of the genotypes deviated from the Hardy-Weinberg equilibrium. At the AACR meeting the genotyping of all subjects will be completed. Conclusions: Our results of vitamin D genotyping will be correlated with BC tumor molecular subtype in affected subjects, and any association with BRCA mutation and outcome will be assessed. The study was funded by IEO Foundation and AVON. Description of vitamin D genetic polymorphisms and their frequenciesSNPsType of polymorphismMinor Allele Frequency (MAF)MAF HapMapHWE Pvalue(1df chi-square test)rs 1544410; VDR BsmITransition C/TT: 0.420.440.50rs2228570; VDR FokITransition A/GA: 0.360.410.72rs731236; VDR TaqITransition A/GC: 0.410.440.52rs7975232; VDR ApaITransversion A/CG: 0.430.430.91rs22282679; GCTransversion G/TG: 0.280.260.52 Citation Format: Valentina Aristarco, Harriet Johansson, Debora Macis, Aliana Guerrieri Gonzaga, Sara Gandini, Davide Serrano, Irene Feroce, Monica Barile, Antonella Puccio, Lorenzo Brocca, Bernardo Bonanni. Associations of Vitamin D related polymorphisms with hereditary breast cancer in 1025 subjects undergoing BRCA 1/2 testing. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1909. doi:10.1158/1538-7445.AM2015-1909

Single nucleotide polymorphisms in the Gc gene for vitamin D binding protein in common cancers in Thailand.

This case-control study aimed to determine if there were any associations between the two single nucleotide polymorphisms (SNPs) in Gc, rs7041 (Asp416Glu) and rs4588 (Thr420Lys) and 3 common cancers (breast, lung and colorectal) in Thai patients. Two hundred and eighty two colorectal, 101 breast and 113 lung cancer patients were recruited from one institute during 2011-2013. The controls were age-matched volunteers who had a negative history of index cancers. In addition, vitamin D levels were compared among different genotypes in the 2 SNPs. The minor allele frequencies of rs7041 (G) and rs4588 (A) were 0.32 and 0.24, respectively. Under the dominant model, the study found significant associations between minor-allele genotypes of the SNP rs7041 (TG/GG) and lung cancer (odds ratio [OR] 1.78, 95% CI 1.05-3.03). When subgroup analysis was performed according to sex and age at diagnosis, the study found that the minor- allele genotypes of rs7041 (TG/GG) were significantly associated with colorectal cancer in patients whose age at diagnosis was more than 60 years (OR 1.67, 95%CI 1.06-2.61) and the minor-allele genotypes of rs4588 (CA/AA) were significantly associated with colorectal cancer in males aged 60 years or less (OR 2.34, 95%CI 1.25-4.37). When SNP combinations (rs7041-rs4588) were examined, the TT-CA combination had a significant protective association with lung cancer (OR 0.44, 95% CI 0.22-0.85). On evaluation of serum 25(OH)D levels in 205 individuals without cancer (males 144, females 61), the proportion of subjects with low serum vitamin D (< 20 ng/ml) in those harboring CA or AA genotypes of rs4588 (41.7%) was significantly higher than the CC genotype (15.5%, p-value < 0.01). Genetic polymorphisms in Gc were associated with lung and colorectal cancers in Thai patients. Lower serum 25(OH)D in minor variants of rs4588 may explain this association.

Genetic and environmental determinants of 25-hydroxyvitamin D levels in multiple sclerosis

Background: Evidence is accumulating supporting a beneficial effect of vitamin D in multiple sclerosis (MS). Genome-wide association studies (GWAS) have shown significant associations between 25-hydroxyvitamin D (25(OH)D) and single nucleotide polymorphisms (SNPs) in key genes in the vitamin D metabolism. Objective: To examine the association between 25(OH)D and six GWAS SNPs and environmental factors in 1497 MS patients. Methods: Blood samples and lifestyle questionnaires were collected between 2009 and 2012. Genotyping of GC-, CYP2R1- and NADSYN1-SNPs was performed by TaqMan allelic discrimination (Life Technologies). Results: We found significant associations between 25(OH)D and SNPs in GC (rs7041, p = 0.01 and rs2282679, p = 0.03) and CYP2R1 (rs10741657, p =1.8 × 10−4). Season of blood sampling (p = 2.8 × 10−31), sex (p = 1.9 × 10−5), BMI (p = 2.3 × 10−5), vitamin supplements (p = 7.0 × 10−22), and fish intake (p = 0.02) also had significant effects on 25(OH)D. Conclusion: In this cross-sectional study, we found significant effects of environmental factors and SNPs in GC and CYP2R1 on 25(OH)D in MS patients. Since 25(OH)D might have protective effects in MS, and vitamin D supply is a modifiable factor, it may be important to include this in the MS treatment regimen.

Environmental and genetic determinants of vitamin D insufficiency in 12-month-old infants

We aimed to investigate the relationship between genetic and environmental exposure and vitamin D status at age one, stratified by ethnicity. This study included 563 12-month-old infants in the HealthNuts population-based study. DNA from participants’ blood samples was genotyped using Sequenom MassARRAY MALDI-TOF system on 28 single nucleotide polymorphisms (SNPs) in six genes. Using logistic regression, we examined associations between environmental exposure and SNPs in vitamin D pathway and filaggrin genes and vitamin D insufficiency (VDI). VDI, defined as serum 25-hydroxyvitamin D3(25(OH)D3) level ≤50nmol/L, was measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Infants were stratified by ethnicity determined by parent’s country of birth. Infants formula fed at 12 months were associated with reduced odds of VDI compared to infants with no current formula use at 12 months. This association differed by ethnicity (Pinteraction=0.01). The odds ratio (OR) of VDI was 0.29 for Caucasian infants (95% CI, 0.18–0.47) and 0.04 for Asian infants (95% CI, 0.006–0.23). Maternal vitamin D supplementation during pregnancy and/or breastfeeding were associated with increased odds of infants being VDI (OR, 2.39; 95% CI, 1.11–5.18 and OR, 2.5; 95% CI, 1.20–5.24 respectively). Presence of a minor allele for any GC SNP (rs17467825, rs1155563, rs2282679, rs3755967, rs4588, rs7041) was associated with increased odds of VDI. Caucasian infants homozygous (AA) for rs4588 had an OR of 2.49 of being associated with VDI (95% CI, 1.19–5.18). In a country without routine infant vitamin D supplementation or food chain fortification, formula use is strongly associated with a reduced risk of VDI regardless of ethnicity. There was borderline significance for an association between filaggrin mutations and VDI. However, polymorphisms in vitamin D pathway related genes were associated with increased likelihood of being VDI in infancy.

Common vitamin D pathway gene variants reveal contrasting effects on serum vitamin D levels in African Americans and European Americans.

Vitamin D deficiency is more common among African Americans (AAs) than among European Americans (EAs), and epidemiologic evidence links vitamin D status to many health outcomes. Two genome-wide association studies (GWAS) in European populations identified vitamin D pathway gene single-nucleotide polymorphisms (SNPs) associated with serum vitamin D [25(OH)D] levels, but a few of these SNPs have been replicated in AAs. Here, we investigated the associations of 39 SNPs in vitamin D pathway genes, including 19 GWAS-identified SNPs, with serum 25(OH)D concentrations in 652 AAs and 405 EAs. Linear and logistic regression analyses were performed adjusting for relevant environmental and biological factors. The pattern of SNP associations was distinct between AAs and EAs. In AAs, six GWAS-identified SNPs in GC, CYP2R1, and DHCR7/NADSYN1 were replicated, while nine GWAS SNPs in GC and CYP2R1 were replicated in EAs. A CYP2R1 SNP, rs12794714, exhibited the strongest signal of association in AAs. In EAs, however, a different CYP2R1 SNP, rs1993116, was the most strongly associated. Our models, which take into account genetic and environmental variables, accounted for 20 and 28 % of the variance in serum vitamin D levels in AAs and EAs, respectively.Electronic supplementary materialThe online version of this article (doi:10.1007/s00439-014-1472-y) contains supplementary material, which is available to authorized users.

Genetic variants in CYP2R1, CYP24A1, and VDR modify the efficacy of vitamin D3 supplementation for increasing serum 25-hydroxyvitamin D levels in a randomized controlled trial.

Adequate serum 25-hydroxyvitamin D concentrations, [25(OH)D], are required for optimal bone health, and low levels are associated with chronic diseases. We investigated whether 41 candidate single nucleotide polymorphisms (SNPs) in vitamin D and calcium pathway genes (GC, DHCR7, CYP2R1, CYP27B1, CYP24A1, VDR, and CASR) are associated with [25(OH)D] or modify the increase in [25(OH)D] from vitamin D3 supplementation. Baseline and year 1 [25(OH)D] measurements from a randomized controlled trial conducted at 11 clinical centers in the United States. A total of 1787 healthy non-Hispanic white participants aged 45-75 years. Vitamin D3 (1000 IU/d), calcium carbonate (1200 mg/d elemental), both, or placebo. Genotype main effects and interactions with vitamin D3 treatment estimated using multiple linear regression. The baseline serum [25(OH)D] was 25.4 ± 8.7 ng/mL (mean ± SD). Associations with baseline levels were discovered for SNPs in CYP24A1 (rs2209314, rs2762939) and confirmed for SNPs in GC and CYP2R1. After 1 year, [25(OH)D] increased on average by 6.1 ± 8.9 ng/mL on vitamin D3 treatment and decreased by 1.1 ± 8.4 ng/mL on placebo. The increase in [25(OH)D] due to vitamin D3 supplementation was modified by genotypes at rs10766197 near CYP2R1, rs6013897 near CYP24A1, and rs7968585 near VDR. The increase in [25(OH)D] attributable to vitamin D3 supplementation may vary according to common genetic differences in vitamin D 25-hydroxylase (CYP2R1), 24-hydroxylase (CYP24A1), and the vitamin D receptor (VDR) genes. These findings have implications for achieving optimal vitamin D status and potentially for vitamin D-related health outcomes.

Effect of vitamin D–binding protein genotype on the development of asthma in children

BackgroundPotential vitamin D–related influences on inflammatory diseases such as asthma are controversial, including the suggestion that vitamin D insufficiency is associated with increased asthma morbidity. Vitamin D–binding protein transports vitamin D metabolites in the circulation. Single nucleotide polymorphisms in the GC gene encoding vitamin D–binding protein are associated with circulating vitamin D metabolite levels in healthy infants and toddlers. ObjectiveTo test the hypothesis that GC single nucleotide polymorphisms encoding the D432E and T436K variants predict subsequent development of asthma in healthy children. MethodsA retrospective medical record review was performed to determine the development of asthma in 776 children in whom GC genotype, vitamin D–binding protein concentration, and circulating 25-hydroxyvitamin D had been determined at 6 to 36 months of age. Demographic and detailed current clinical data were collected and criteria for asthma were recorded. ResultsGC genotype was available for 463 subjects. After an initial analysis of all subject data, the analysis was limited to the predominant Hispanic population (72.1%) to minimize potential confounding effects of ethnicity. Asthma was diagnosed in 87 children (26%). Subjects with the GC genotype encoding the ET/ET (Gc1s/Gc1s) variant had lower odds of developing asthma, representing a protective effect compared with subjects with the DT/DT (Gc1f/Gc1f) variant. ConclusionIn the Hispanic population of inner-city New Haven, Connecticut, the ET/ET (Gc1s/Gc1s) genotype of vitamin D–binding protein might confer protection against the development of asthma compared with the wild-type genotype DT/DT (Gc1f/Gc1f).

Abstract 2196: Genetic correlates of serum 25-hydroxyvitamin D levels and response to vitamin D supplementation.

Abstract Epidemiological studies indicate that vitamin D has antineoplastic effects in the colorectum and suggest that vitamin D supplementation may be a promising chemopreventative approach to reduce risk of colorectal cancer. Thus, it is important to consider how genetic factors may modify vitamin D status and response to vitamin D supplementation. We investigated this question among 2,259 participants randomized in the Vitamin D/Calcium Polyp Prevention Study, an on-going, double-blind, placebo-controlled clinical trial of supplementation with vitamin D3 (1000 IU/day) and/or calcium carbonate (1200 mg elemental calcium/day) for the prevention of colorectal adenomas. Candidate single nucleotide polymorphisms (SNPs) were genotyped in or near seven genes involved in vitamin D or calcium metabolism, transport or signaling. Excluding SNPs with MAF&amp;lt;5% and r2&amp;gt;0.8, 23 SNPs were analyzed in vitamin D binding protein (GC), 25-hydroxylase (CYP2R1), 24-hydroxylase (CYP24A1), 1-hydroxylase (CYP27B1), 7-dehydrocholesterol reductase (DHCR7), vitamin D receptor (VDR), and calcium-sensing receptor (CaSR). These included 5 SNPs previously associated with circulating 25-hydroxyvitamin D levels in genome-wide association studies (GWAS): rs2282679, rs12785878, rs3829251, rs10741657 and rs6013897. Linear regression was used to estimate associations with baseline serum 25-hydroxyvitamin D levels and with levels of 25-hydroxyvitamin D achieved after approximately one year of vitamin D supplementation in the trial after adjusting for baseline levels. Analyses were restricted to non-Hispanic white participants (82%) to avoid population stratification and additive genetic models were used. Baseline 25-hydroxyvitamin D was statistically significantly associated with genotype at 3 GWAS hits in GC, DHCR7 and CYP2R1 and at 5 other SNPs in GC, CYP2R1 and CYP24A1. When response to supplementation was investigated, compliance with pill taking was taken into account by restricting analyses to optimally compliant subjects. Genotype at 3 SNPs in VDR, CYP2R1, and CYP24A1 statistically significantly modified the 25-hydroxyvitamin D level achieved with vitamin D supplementation. In conclusion, we have identified variation in or near key vitamin D and calcium pathway genes that modify serum 25-hydroxyvitamin D status and the response to supplementation with vitamin D. This research may identify individuals at risk for poor response to vitamin D supplementation. The public health significance of this work is substantial due to the prevalence of vitamin D insufficiency and the high incidence of colorectal cancer, osteoporosis, and other common diseases associated with poor vitamin D status. Citation Format: Elizabeth L. Barry, Leila A. Mott, Janet L. Peacock, Judith R. Rees, John A. Baron. Genetic correlates of serum 25-hydroxyvitamin D levels and response to vitamin D supplementation. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2196. doi:10.1158/1538-7445.AM2013-2196

Vitamin D Intake and Season Modify the Effects of the GC and CYP2R1 Genes on 25-Hydroxyvitamin D Concentrations

Vitamin D deficiency {defined by the blood concentration of 25-hydroxyvitamin D [25(OH)D]} has been associated with many adverse health outcomes. Genetic and nongenetic factors account for variation in 25(OH)D, but the role of interactions between these factors is unknown. To assess this, we examined 1204 women of European descent from the Carotenoids in Age-Related Eye Disease Study, an ancillary study of the Women's Health Initiative Observational Study. Twenty-nine single nucleotide polymorphisms (SNPs) in 4 genes, GC, CYP2R1, DHCR7, and CYP24A1, from recent meta-analyses of 25(OH)D genome-wide association studies were genotyped. Associations between these SNPs and 25(OH)D were tested using generalized linear regression under an additive genetic model adjusted for age, blood draw month, and ancestry. Results were stratified by season of blood draw and, separately, vitamin D intake for the 6 SNPs showing a significant association with 25(OH)D at the P < 0.01 level. Two nonsynonymous SNPs in GC and 4 SNPs in CYP2R1 were strongly associated with 25(OH)D in individuals whose blood was drawn in summer (P ≤ 0.002) but not winter months and, independently, in individuals with vitamin D intakes ≥400 (P ≤ 0.004) but not <400 IU/d (10 μg/d). This effect modification, if confirmed, has important implications for the design of genetic studies for all health outcomes and for public health recommendations and clinical practice guidelines regarding the achievement of adequate vitamin D status.

Vitamin D binding protein is a key determinant of 25-hydroxyvitamin D levels in infants and toddlers

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.

Genetic predictors of 25-hydroxyvitamin D levels and risk of multiple sclerosis

Risk of multiple sclerosis (MS) decreases with increasing plasma levels of 25-hydroxyvitamin D [25(OH)D]. If this association reflected a protective effect of vitamin D, MS risk should be lower among individuals carrying genetic variants that predict high 25(OH)D levels. The aim of the study was to determine whether individuals with genotypes predicting higher 25(OH)D levels have decreased MS risk. Logistic regression was used to assess the association between single nucleotide polymorphisms (SNPs) associated with 25(OH)D levels and MS risk in 1,655 cases and 6,349 controls. Analyses were further stratified by HLA-DR15 status, assessed by genotyping a single SNP strongly correlated with the HLA DRB1 1501 risk haplotype, and complemented by considering a SNP near CYP27B1. SNPs in GC were predictors of 25(OH)D levels, but not MS risk, in either HLA-DR15 negative or HLA-DR15 positive individuals. In contrast, there was a suggestion of a difference in the effect of a CYP2R1 allele dependent on HLA-DR15 genotype. The 'A' allele of CYP2R1 rs10741657 was associated with increased 25(OH)D levels and a non-significant reduced MS risk among HLA-DR15 negative (OR = 0.89, 95% CI: 0.79, 1.01) that was not apparent in HLA-DR15 positive individuals. The 'C' allele of CYP27B1 rs703842 was inversely associated with MS risk; this association appeared stronger among HLA-DR15 negative (OR = 0.79, 95% CI: 0.69, 0.90) compared to HLA-DR15 positive individuals (OR = 0.91, 95% CI: 0.80, 1.04). This preliminary finding suggests the possibility that the putative beneficial effect of vitamin D on MS risk maybe attenuated in individuals carrying the HLA-DR15 MS risk allele.