25-hydroxyvitamin D levels, vitamin D binding protein gene polymorphisms and incident coronary heart disease among whites and blacks: The ARIC study.
ABSTRACT: BACKGROUND:In observational studies, low 25-hydroxyvitamin D (25(OH)D) has been associated with increased risk of coronary heart disease (CHD), and this association may vary by race. Racial differences in the frequency of vitamin D binding protein (DBP) single nucleotide polymorphisms (SNPs) might account for similar bioavailable vitamin D in blacks despite lower mean 25(OH)D. We hypothesized that the associations of low 25(OH)D with CHD risk would be stronger among whites and among persons with genotypes associated with higher DBP levels. METHODS:We measured 25(OH)D by mass spectroscopy in 11,945 participants in the ARIC Study (baseline 1990-1992, mean age 57 years, 59% women, 24% black). Two DBP SNPs (rs7041; rs4588) were genotyped. We used adjusted Cox proportional hazards models to examine the association of 25(OH)D with adjudicated CHD events through December 2011. RESULTS:Over a median of 20 years, there were 1230 incident CHD events. Whites in the lowest quintile of 25(OH)D (<17 ng/ml) compared to the upper 4 quintiles had an increased risk of incident CHD (HR 1.28, 95% CI 1.05-1.56), but blacks did not (1.03, 0.82-1.28), after adjustment for demographics and behavioral/socioeconomic factors (p-interaction with race = 0.22). Results among whites were no longer significant after further adjustment for potential mediators of this association (i.e. diabetes, hypertension). There was no statistically significant interaction of 25(OH)D with the DBP SNPs rs4588 (p = 0.92) or rs7041 (p = 0.87) in relation to CHD risk. CONCLUSIONS:Low 25(OH)D was associated with incident CHD in whites, but no interactions of 25(OH)D with key DBP genotypes was found.
Project description:BACKGROUND:Low 25-hydroxyvitamin D [25(OH)D] is associated with diabetes, but few studies have examined racially diverse populations while also accounting for key vitamin D-binding protein (DBP) gene polymorphisms. OBJECTIVE:We sought to evaluate whether the association between 25(OH)D and incident diabetes varied by race and important DBP single nucleotide polymorphisms (SNPs). DESIGN:We studied 10,222 adults (8120 whites, 2102 blacks) aged 46-70 y at baseline (1990-1992) from the ARIC (Atherosclerosis Risk in Communities) Study with follow-up for incident diabetes ascertained during study visits conducted in 1993-1995 and 1996-1998. Adjusted HRs and their 95% CIs for diabetes were estimated according to 25(OH)D status. RESULTS:During follow-up there were 750 incident cases of diabetes. The association of 25(OH)D with diabetes varied by race (P-interaction = 0.004). Among whites, the adjusted HR for diabetes corresponding to each additional SD higher 25(OH)D concentration (21.3 nmol/L) was 0.95 (95% CI: 0.91, 0.99). No significant association was observed among blacks (HR: 1.06; 95% CI: 0.99, 1.14). There was evidence that the A allele at rs4588 and the T allele at rs7041, which are reported to be associated with high and low DBP concentrations, respectively, modified the association between 25(OH)D and diabetes among whites (P-interaction < 0.05 for both) but not blacks (P-interaction > 0.50 for both). CONCLUSIONS:In this large, community-based study, low 25(OH)D concentrations were associated with diabetes among whites but not blacks. Interactions by key DBP SNPs varied between genotypes associated with either high or low DBP concentrations among whites but not blacks. Nevertheless, the findings from this prospective study suggest that there are important differences in the association of 25(OH)D with incident diabetes between white and black adults.
Project description:BACKGROUND:Deficient levels of 25-hydroxyvitamin D [25(OH)D] have been associated with increased fracture risk. Racial differences in fracture risk may be related to differences in bioavailable vitamin D due to single nucleotide polymorphism (SNP) variations in the vitamin D binding protein (DBP). METHODS:We measured 25(OH)D levels in 12,781 middle-aged White and Black participants [mean age 57 years (SD 5.7), 25% Black] in the ARIC Study who attended the second examination from 1990-1992. Participants were genotyped for two DBP SNPs (rs4588 and rs7041). Incident hospitalized fractures were measured by abstracting hospital records for ICD-9 codes. We used Cox proportional hazards models to evaluate the association between 25(OH)D levels and risk of fracture with adjustment for possible confounders. Interactions were tested by race and DBP genotype. RESULTS:There were 1122 incident fracture-related hospitalizations including 267 hip fractures over a median of 19.6 years of follow-up. Participants with deficient 25(OH)D (<20 ng/mL) had a higher risk of any fracture hospitalization [HR=1.21 (95% CI 1.05-1.39)] and hospitalization for hip fracture [HR=1.35 (1.02-1.79)]. No significant racial interaction was noted (p-interaction=0.20 for any fracture; 0.74 for hip fracture). There was no independent association of rs4588 and rs7041 with fracture. However, there was a marginal interaction for 25(OH)D deficiency with rs7041 among Whites (p-interaction=0.065). Whites with both 25(OH)D deficiency and the GG genotype [i.e., with predicted higher levels of DBP and lower bioavailable vitamin D] were at the greatest risk for any fracture [HR=1.48 (1.10-2.00)] compared to Whites with the TT genotype and replete 25(OH)D (reference group). CONCLUSIONS:Deficient 25(OH)D levels are associated with higher incidence of hospitalized fractures. Marginal effects were seen in Whites for the DBP genotype associated with lower bioavailable vitamin D, but result inconclusive. Further investigation is needed to more directly evaluate the association between bioavailable vitamin D and fracture risk.
Project description:BACKGROUND AND PURPOSE:Low vitamin D levels, measured by serum 25-hydroxyvitamin D [25(OH)D], are associated with increased stroke risk. Less is known about whether this association differs by race or D binding protein (DBP) single nucleotide polymorphism (SNP) status. Our objective was to characterize the associations of and interactions between 25(OH)D levels and DBP SNPs with incident stroke. It was hypothesized that associations of low 25(OH)D with stroke risk would be stronger amongst persons with genotypes associated with higher DBP levels. METHODS:25(OH)D was measured by mass spectroscopy in 12 158 participants in the Atherosclerosis Risk in Communities (ARIC) study (baseline 1990-1992, mean age 57 years, 57% female, 23% black) and they were followed through 2011 for adjudicated stroke events. Two DBP SNPs (rs7041, rs4588) were genotyped. Cox models were adjusted for demographic/behavioral/socioeconomic factors. RESULTS:During a median of 20 years follow-up, 804 incident strokes occurred. The lowest quintile of 25(OH)D (<17.2 ng/ml) was associated with higher stroke risk [hazard ratio (HR) 1.34 (1.06-1.71) versus highest quintile]; this association was similar by race (P interaction 0.60). There was weak evidence of increased risk of stroke amongst those with 25(OH)D < 17.2 ng/ml and either rs7041 TG/GG [HR = 1.29 (1.00-1.67)] versus TT genotype [HR = 1.19 (0.94-1.52)] (P interaction 0.28) or rs4588 CA/AA [HR = 1.37 (1.07-1.74)] versus CC genotype [HR = 1.14 (0.91-1.41)] (P interaction 0.11). CONCLUSIONS:Low 25(OH)D is a risk factor for stroke. Persons with low 25(OH)D who are genetically predisposed to high DBP (rs7041 G, rs4588 A alleles), who therefore have lower predicted bioavailable 25(OH)D, may be at greater risk for stroke, although our results were not conclusive and should be interpreted as hypothesis generating.
Project description:Blacks have different dominant polymorphisms in the vitamin D-binding protein (DBP) gene that result in higher bioavailable vitamin D than whites. This study tested whether the lack of association between 25-hydroxyvitamin D (25OHD) and multiple sclerosis (MS) risk in blacks and Hispanics is due to differences in these common polymorphisms (rs7041, rs4588). We recruited incident MS cases and controls (blacks 116 cases/131 controls; Hispanics 183/197; whites 247/267) from Kaiser Permanente Southern California. AA is the dominant rs7041 genotype in blacks (70.0%) whereas C is the dominant allele in whites (79.0% AC/CC) and Hispanics (77.1%). Higher 25OHD levels were associated with a lower risk of MS in whites who carried at least one copy of the C allele but not AA carriers. No association was found in Hispanics or blacks regardless of genotype. Higher ultraviolet radiation exposure was associated with a lower risk of MS in blacks (OR = 0.06), Hispanics and whites who carried at least one copy of the C allele but not in others. Racial/ethnic variations in bioavailable vitamin D do not explain the lack of association between 25OHD and MS in blacks and Hispanics. These findings further challenge the biological plausibility of vitamin D deficiency as causal for MS.
Project description:OBJECTIVES:This study sought to determine if low serum 25-hydroxyvitamin D (25[OH]D) is associated with incident heart failure (HF) and if the association is: 1) partly mediated by traditional cardiovascular risk factors; 2) stronger among whites than blacks; and 3) stronger among those genetically predisposed to having high levels of vitamin D binding protein (DBP). BACKGROUND:Suboptimal 25(OH)D is a potential cardiovascular risk factor. METHODS:A total of 12,215 ARIC (Atherosclerosis Risk in Communities) study participants free of HF at baseline (1990 to 1992; median age, 56; 24% black) were followed through 2010. Total serum 25(OH)D was measured at baseline using liquid chromatography-mass spectrometry. Incident HF events were identified by a hospital discharge code of ICD9-428 and parallel International Classification of Diseases codes for HF deaths. RESULTS:During 21 years of follow-up, 1,799 incident HF events accrued. The association between 25(OH)D and HF varied by race (p-interaction = 0.02). Among whites, risk was 2-fold higher for those in the lowest (?17 ng/ml) versus highest (?31 ng/ml) quintile of 25(OH)D. The association was attenuated but remained significant with covariate adjustment. In blacks there was no overall association. In both races, those with low 25(OH)D and the rs7041 G allele, which predisposes to high DBP, were at greater risk (p-interaction = 0.01). CONCLUSIONS:Low serum 25(OH)D was independently associated with incident HF among whites, but not among blacks. However, in both races, low 25(OH)D was associated with HF risk among those genetically predisposed to high DBP. These findings provide novel insight into metabolic differences that may underlie racial variation in the association between 25(OH)D and cardiovascular risk.
Project description:Abstract Vitamin D binding protein (DBP) is one of regulators of vitamin D serum levels. rs4588 and rs7041 polymorphisms of the DBP gene constitute the genetic basis of the three major isoforms of circulating DBP, called GC1s, GC1f and GC2. We evaluated the association between the rs4588, rs7041, rs2282679 SNPs and of DBP isoforms with DBP and 25(OH)D serum levels and investigated whether these gene variants influence on the presence of vitamin D deficiency in a non-selected women sample. In this cross-sectional study, bio-repository samples of 443 apparently healthy women aged 20 to 72 years were analyzed. Most of the participants were ppostmenopausal (n=359). Sufficient circulating levels of 25(OH)D was considered as ?20ng/mL and deficiency as <20ng/mL. Clinical and biochemical profile were collected. Participants were genotyped for rs4588, rs7041, and rs2282679 polymorphisms by RT-PCR. BDP isoforms were constructed from the combination of the rs4588 and rs7041 polymorphisms, where GC1s= rs4588CC and rs7041GG; GC1f= rs4588CC and rs7041TT and Gc2= rs4588AA and rs7041TT. Mean age and BMI were 53.4±9.4 years and 27.8±5.8, respectively. 25(OH)D levels in total sample was 22.8±8.3ng/mL and 60% had adequate circulating 25(OH)D levels. rs4588, rs2282679 SNPs and the GC2 isoforms were associated with lower DBP levels (rs4588: CC=203.0±28.3; CA=196.5±29.9; AA=184.0±36.9; linear p trend<0.001, B=-8.4; rs2282679: AA=203.1±27.9; AC=196.4±30.0; CC=180.9±38.2; linear p trend<0.001, B=-9.3; and DBP isoforms: GC1s=199.4±29.9; GC1f=204.8±31.6; GC2=180.8±37.6; linear p trend=0.012, B=-7.7) and rs2282689 as well as GC2 isoform were associated with lower 25(OH)D levels (rs2282679: AA=23.4±8.8; AC=22.8±7.8; CC=19.7±7.2; linear p trend=0.034, B=-1.3; and DBP isoforms: GC1s=23.8±9.2; GC1f=20.6±8.3; GC2=20.3±7.4; linear p trend=0.015, B=-1.9). CC genotype of rs2282679 (PR 1.74; 95%CI 1.30;2.24; p<0.001), GC2 isoform (PR 1.66; 95%CI 1.17; 2.38; p=0.005), time since menopause (PR 1.02; 95%CI 1.003;1.03, p= 0.016) and HOMA-IR (PR 1.02; 95%CI 1.01;1.03, p= 0.004) were associated with higher prevalence ratios for 25(OH)D deficiency. DBP levels (per 30 ug/mL of DBP increase, PR 0.89; 95%CI 0.80;0.99; p=0.027) were related to lower prevalence ratios for 25(OH)D deficiency. Except for HOMA-IR, these PR remained significant after adjustment for age and BMI. In conclusion, the present results suggest that rs2282679 and the GC2 isoform of DBP are related to lower DBP serum levels and with the susceptibility to 25(OH)D deficiency in adult and postmenopausal women. Support: CNPq, FAPERGS and FIPE/HCPA
Project description:In addition to its role as a transport protein, the vitamin D binding protein (DBP) may also affect lipid metabolism, inflammation and carcinogenesis. There are three common variants of the DBP, Gc1s (1s), Gc1f (1f), Gc2 (2) that result in six common phenotypes (1s/1s, 1s/1f, 1s/2, 1f/1f, 1f/2, and 2/2). These phenotypes can be identified by genotyping for the two single nucleotide polymorphisms rs7041 and rs4588 in the GC gene. The DBP variants have different binding coefficients for the vitamin D metabolites, and accordingly there may be important relations between DBP phenotypes and health.DNA was prepared from subjects who participated in the fourth survey of the Tromsø Study in 1994-1995 and who were registered with the endpoints myocardial infarction (MI), type 2 diabetes (T2DM), cancer or death as well as a randomly selected control group. The endpoint registers were complete up to 2010- 2013. Genotyping was performed for rs7041 and rs4588 and serum 25-hydroxyvitamin D (25(OH)D) was measured.Genotyping for rs7041 and rs4588 was performed successfully in 11 704 subjects. Among these, 1660 were registered with incident MI, 958 with T2DM, 2410 with cancer and 4318 had died. Subjects with the DBP phenotype 1f/1f had 23 - 26 % reduced risk of incident cancer compared to the 1s/1s and 2/2 phenotypes (P < 0.02, Cox regression with gender as covariate). Differences in serum 25(OH)D levels could not explain the apparent cancer protective effect of the DBP variant 1f. In addition to cancer and 25(OH)D, there were significant associations between DBP phenotype and body height, hip circumference and serum calcium.There are important biological differences between the common DBP phenotypes. If the relation between the DBP variant 1f and cancer is confirmed in other studies, determination of DBP phenotype may have clinical importance.
Project description:Vitamin D deficiency has been related to metabolic syndrome (MetS) in polycystic ovary syndrome (PCOS). The vitamin D-binding protein (DBP) is the main protein involved in vitamin D transport. Two single-nucleotide polymorphisms (SNPs) of the DBP gene, rs4588 and rs7041, have been associated with low circulating levels of 25-hydroxyvitamin D [25(OH)D] in various populations, but not in women with PCOS. Therefore, we determined the genotype and haplotype distribution of DBP gene polymorphisms and investigated the associations between these genetic variants and their haplotypes with PCOS, MetS, and 25(OH)D levels in women with PCOS and controls from the South of Brazil. The sample included 291 women (191 with PCOS and 100 controls). All participants were genotyped for polymorphisms rs2282679, rs4588, and rs7041. Serum 25(OH)D levels were determined in a subset of 102 participants. Women with PCOS were younger and had significantly higher body mass index, blood pressure, and insulin resistance than the control group (p<0.05). The prevalence of MetS in PCOS and controls was 26.5% and 4.8% respectively. Levels of 25(OH)D were lower in PCOS women with MetS, even after adjustment for age (p = 0.033). No associations were observed between PCOS and the polymorphisms or their haplotypes. A higher frequency of genotype TT of rs7041 was found in PCOS participants with MetS (OR: 2.21, 95%CI:1.08-4.52; p = 0.027). This same genotype was associated with lower 25(OH)D levels in both PCOS and control women (OR: 4.40, 95%CI:1.62-12.00; p = 0.002). In conclusion, these findings indicate that DBP gene polymorphisms and their haplotypes are not directly associated with PCOS. In contrast, the TT genotype of SNP rs7041 was associated with MetS in PCOS women, and with lower 25(OH)D levels in both PCOS and control groups.
Project description:AbstractThe 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 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 gene are associated with baseline 25(OH)D levels and modifies 25(OH)D response after vitamin D supplementation in Saudi adults.
Project description:Introduction:Sarcoidosis is a rare multisystem granulomatous disease with unknown etiology. The interplay of vitamin D deficiency and genetic polymorphisms in genes coding for the proteins relevant for metabolism of vitamin D is an important, but unexplored area. The aim of this study was to investigate the association between single nucleotide polymorphisms (SNPs) in CYP2R1 (rs10741657), CYP27B1 (rs10877012), DBP (rs7041; rs4588), and VDR (rs2228570) genes and sarcoidosis, as well as the association between these SNPs and 25(OH)D levels in sarcoidosis patients. Material and methods:For that purpose we genotyped 86 sarcoidosis patients and 50 healthy controls using the PCR-RFLP method. Results:Subjects carrying the CC genotype of CYP27B1 rs10877012 have 10 times lower odds of suffering from sarcoidosis. Moreover, DBP rs4588 AA genotype was shown to be a susceptibility factor, where carriers of this genotype had eight times higher odds for developing sarcoidosis. In addition, the A allele of the DBP gene (rs4588) was associated with lower levels of 25(OH)D in sarcoidosis patients. Conclusions:These results suggest that patients with vitamin D deficiency should be regularly tested for genetic modifiers that are related to sarcoidosis in order to prevent development of serious forms of sarcoidosis.