Vitamin D levels and Vitamin D-related gene polymorphisms in Chinese children with type 1 diabetes

Low vitamin D levels may play a role in type 1 diabetes (T1D) susceptibility. Since 25(OH)D synthesis is genetically regulated, single nucleotide polymorphisms (SNPs) of important genes have also been shown to modulate the risk of T1D, so this study aimed to investigate the relationship between five SNPs in CYP2R1, DHCR7, CYP24A1, VDR genes, serum 25(OH)D levels and T1D in Chinese children. This case-control study included 141 T1D patients and 200 age-matched healthy children.25 (OH) D concentration was determined, genotyping was performed by High resolution melting (HRM). There was a significant difference in the prevalence of vitamin D deficiency, insufficiency, and sufficiency between T1D and healthy controls. (χ ² = 10.86, p = 0.004), however no evidence of the association between any group of SNPs and circulating 25(OH) D levels was observed. The allele distribution of CYP2R1(rs1993116) was significantly different between T1D and control group (p = 0.040), and the C allele carriers of rs1993116 had a higher risk of T1D than the T allele carriers, Carriers of the CC and CT genotypes of rs1993116 have higher T1D risk than those carrying the TT genotype. GMDR analysis revealed a significant interaction between CYP2R1(rs12794714) and CYP2R1(rs1993116) in the risk of T1D with a maximum testing balance accuracy of 60.39%.

New Variants of the Cytochrome P450 2R1 (CYP2R1) Gene in Individuals with Severe Vitamin D-Activating Enzyme 25(OH)D Deficiency

BACKGROUND

Vitamin D is a fat-soluble cholesterol derivative found in two forms, vitamin D2, and vitamin D3. Cytochrome P450 2R1 (CYP2R1) encoded by the CYP2R1 gene is the major hydroxylase that activates vitamin D by catalyzing the formation of 25-hydroxyvitamin D (25(OH)D).

METHODS

We collected 89 (100%) subjects, 46 of which (51.69%) had a documented severe deficiency of 25(OH)D (<10 ng/mL) and 43 (48.31%) in the control group with documented optimum levels of 25(OH)D (>30 ng/mL). We performed Sanger sequencing of three selected fragments of the CYP2R1 gene (Ch11: 14878000-14878499; Ch11: 14880058-14880883 and Ch11: 14885321-14886113) that affect the binding of substrates to this enzyme and analyzed the possible involvement of genetic variation in these regions with an increased risk of vitamin D deficiency in healthy Polish individuals.

RESULTS

Two substitutions were found within the three fragments. Bioinformatic analysis suggested that one of these (NC_000011.10: g.14878291G>A) may influence the structure and function of CYP2R1.

CONCLUSIONS

Variant NC_000011.10: g.14878291G>A may have a perturbing effect on heme binding in the active site of CYP2R1 and on the function of 25-hydroxylase and probably affects the concentration of 25(OH)D in vivo. We intend to perform functional verification in a larger patient population to confirm and extend these results.

Vitamin D and Type 1 Diabetes Risk: A Systematic Review and Meta-Analysis of Genetic Evidence

Several observational studies have examined vitamin D pathway polymorphisms and their association with type 1 diabetes (T1D) susceptibility, with inconclusive results. We aimed to perform a systematic review and meta-analysis assessing associations between selected variants affecting 25-hydroxyvitamin D [25(OH)D] and T1D risk. We conducted a systematic search of Medline, Embase, Web of Science and OpenGWAS updated in April 2021. The following keywords “vitamin D” and/or “single nucleotide polymorphisms (SNPs)” and “T1D” were selected to identify relevant articles. Seven SNPs (or their proxies) in six genes were analysed: CYP2R1 rs10741657, CYP2R1 (low frequency) rs117913124, DHCR7/NADSYN1 rs12785878, GC rs3755967, CYP24A1 rs17216707, AMDHD1 rs10745742 and SEC23A rs8018720. Seven case-control and three cohort studies were eligible for quantitative synthesis (n = 10). Meta-analysis results suggested no association with T1D (range of pooled ORs for all SNPs: 0.97–1.02; p > 0.01). Heterogeneity was found in DHCR7/NADSYN1 rs12785878 (I²: 64.8%, p = 0.02). Sensitivity analysis showed exclusion of any single study did not alter the overall pooled effect. No association with T1D was observed among a Caucasian subgroup. In conclusion, the evidence from the meta-analysis indicates a null association between selected variants affecting serum 25(OH)D concentrations and T1D.

Impact of Genetic Polymorphisms on the Metabolic Pathway of Vitamin D and Survival in Non-Small Cell Lung Cancer

Vitamin D has been associated with risk, development, and progression of cancer. However, the genes involved in its metabolism are highly polymorphic, compromising its activity. The aim of this study is to evaluate the association between the gene polymorphisms involved in the metabolic pathway of vitamin D and survival in patients with non-small-cell lung cancer (NSCLC). The study was designed as an observational cohort which included 194 Caucasians patients from southern Spain with NSCLC. Real-time polymerase chain reaction was used to analyze the following polymorphisms: CYP27B1 rs4646536, rs3782130, and rs10877012; CYP24A1 rs6068816 and rs4809957; GC rs7041; CYP2R1 rs10741657; VDR rs1544410 (BsmI), rs11568820 (Cdx-2), rs2228570 (FokI), rs7975232 (ApaI), and rs731236 (TaqI). Progression-free survival (PFS) and overall survival were assessed. Cox regression showed that rs4646536 was associated with PFS in the general population (p = 0.0233) and in the non-resected NSCLC subgroup (p = 0.0233). In the resected NSCLC subgroup, rs11568820 was associated with OS (p = 0.0129) and rs7041 with PFS (p = 0.0447). In the non-resected NSCLC subgroup, rs6068816 was associated with PFS (p = 0.0048) and OS (p = 0.0089) and rs731236 and rs7975232 were associated with OS (p = 0.0005) and PFS (p = 0.0002), respectively. The other polymorphisms showed no effect on the results. The rs4646536, rs6068816, rs7041, rs11568820, rs731236, and rs7975232 polymorphisms are associated with survival in NSCLC and may have a substantial role as prognostic markers of the disease.

Association between Polymorphisms in Vitamin D Pathway-Related Genes, Vitamin D Status, Muscle Mass and Function: A Systematic Review

An association between vitamin D level and muscle-related traits has been frequently reported. Vitamin D level is dependent on various factors such as sunlight exposure and nutrition. But also on genetic factors. We, therefore, hypothesize that single nucleotide polymorphisms (SNPs) within the vitamin D pathway-related genes could contribute to muscle mass and function via an impact on vitamin D level. However, the integration of studies investigating these issues is still missing. Therefore, this review aimed to systematically identify and summarize the available evidence on the association between SNPs within vitamin D pathway-related genes and vitamin D status as well as various muscle traits in healthy adults. The review has been registered on PROSPERO and was conducted following PRISMA guidelines. In total, 77 studies investigating 497 SNPs in 13 different genes were included, with significant associations being reported for 59 different SNPs. Variations in GC, CYP2R1, VDR, and CYP24A1 genes were reported most frequently, whereby especially SNPs in the GC (rs2282679, rs4588, rs1155563, rs7041) and CYP2R1 genes (rs10741657, rs10766197, rs2060793) were confirmed to be associated with vitamin D level in more than 50% of the respective studies. Various muscle traits have been investigated only in relation to four different vitamin D receptor (VDR) polymorphisms (rs7975232, rs2228570, rs1544410, and rs731236). Interestingly, all of them showed only very low confirmation rates (6-17% of the studies). In conclusion, this systematic review presents one of the most comprehensive updates of the association of SNPs in vitamin D pathway-related genes with vitamin D status and muscle traits in healthy adults. It might be used for selecting candidate SNPs for further studies, but also for personalized strategies in identifying individuals at risk for vitamin D deficiency and eventually for determining a potential response to vitamin D supplementation.

New insights into vitamin D regulation: is there a role for alkaline phosphatase?

PURPOSE

The diagnosis of vitamin D deficiency is based on the determination of total plasma 25-hydroxyvitamin D (25-OHD) concentrations, but the regulation of vitamin D 25-hydroxylation is not a major consideration and very little information is available on this activity. To check what factors could interfere with the activity of vitamin D-25-hydroxylase and thus alter the 25-OHD concentrations, we looked for potential correlations between 25-OHD and results of liver function tests in healthy adults.

METHODS

This single-centre study was retrospective and consisted of evaluating the correlations between 25-OHD and the activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transpeptidase (GGT), alkaline phosphatase (ALP), and bone alkaline phosphatase (BALP) in 349 healthy subjects aged from 18 to 65 years. In particular, in Group 1 (n = 119), we looked for correlations between 25OHD and all liver function tests and in Group 2 (n = 230) the correlation between 25OHD and BALP.

RESULTS

In Group 1, we found no correlation between 25OHD and AST (r =  - 0.03; p = 0.8), ALT (r =  - 0.02; p = 0.91), GGT (r =  - 0.08; p = 0.68), direct bilirubin (r =  - 0.02; p = 0.89), indirect bilirubin (r =  - 0.24; p = 0.21), and total bilirubin (r =  - 0.24; p = 0.21) but one between 25OHD and ALP (r =  - 0.2; p = 0.007); in Group 2, we found a significant negative correlation between 25-OHD and BALP (r =  - 0.2; p = 0.0008).

CONCLUSIONS

The correlations that we found suggest that ALP and BALP might be involved in the regulation of vitamin D-25-hydroxylase activity, but further studies are mandatory to confirm our assumptions.

Association of Vitamin D, Zinc and Selenium Related Genetic Variants With COVID-19 Disease Severity

Background: COVID-19 pandemic has proved to be an unrelenting health threat for more than a year now. The emerging amount of data indicates that vitamin D, zinc and selenium could be important for clinical presentation of COVID-19. Here, we investigated association of genetic variants related to the altered level and bioavailability of vitamin D, zinc and selenium with clinical severity of COVID-19. Methods: We analyzed variants in genes significant for the status of vitamin D (DHCR7/NADSYN1 rs12785878, GC rs2282679, CYP2R1 rs10741657, and VDR rs2228570), zinc (PPCDC rs2120019) and selenium (DMGDH rs17823744) in 120 Serbian adult and pediatric COVID-19 patients using allelic discrimination. Furthermore, we carried out comparative population genetic analysis among European and other worldwide populations to investigate variation in allelic frequencies of selected variants. Results: Study showed that DHCR7/NADSYN rs12785878 and CYP2R1 rs10741657 variants were associated with severe COVID-19 in adults (p = 0.03, p = 0.017, respectively); carriers of DHCR7/NADSYN TG+GG and CYP2R1 GG genotypes had 0.21 and 5.9 the odds for developing severe disease, OR 0.21 (0.05-0.9) and OR 5.9 (1.4-25.2), respectively. There were no associations between selected genetic variants and disease severity in pediatric patients. Comparative population genetic analysis revealed that Serbian population had the lowest frequency of CYP2R1 rs10741657 G allele compared to other non-Finish Europeans (0.58 compared to 0.69 and 0.66 in Spanish and Italian population, respectively), suggesting that other populations should also investigate the relationship of CYP2R1 variant and the COVID-19 disease course. Conclusion: The results of the study indicated that vitamin D related genetic variants were implicated in severe COVID-19 in adults. This could direct prevention strategies based on population specific nutrigenetic profiles.

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

Background

Group-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.

Methods

This 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.

Results

Minor 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.

Conclusion

The 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.

SNP rs12794714 of CYP2R1 is associated with serum vitamin D levels and recurrent spontaneous abortion (RSA): a case-control study

PURPOSE

Vitamin D (VD) deficiency seems to be associated with the risk of recurrent spontaneous abortion (RSA). Vitamin D receptor (VDR) and cytochrome P450 family 2 subfamily R member 1 (CYP2R1) are two genes which are vital for VD metabolism and actions. However, whether single-nucleotide polymorphisms (SNPs) in these genes are correlated with the risk of RSA are poorly understood. Therefore, we aimed to characterize the relationships among VDR SNPs, CYP2R1 SNPs and RSA.

METHODS

This case-control study enrolled 75 RSA patients and 83 controls. Serum VD and some cytokines were detected with LC-MS/MS and flow cytometry, respectively. Genotyping for three SNPs of CYP2R1 (rs10741657, rs10766197 and rs12794714) and five SNPs of VDR (rs7975232, rs1544410, rs2189480, rs2228570 and rs2239179) was done with polymerase chain reaction (PCR) and high-throughput sequencing. All the data were analyzed with appropriate methods and in different models.

RESULTS

The results revealed a significant correlation between the AG genotype of CYP2R1 rs12794714 and VD levels (OR 0.686; 95% CI 0.49-0.96; p = 0.028). Besides, the AG and GG genotypes of CYP2R1 rs12794714 were markedly related to the risk of RSA (OR 52.394, 59.497; 95% CI 2.683-1023.265, 3.110-1138.367; p = 0.009, 0.007, respectively).

CONCLUSION

Our results indicate that CYP2R1 rs12794714 might be a risk factor for RSA. Hence, early screening of pregnant women for CYP2R1 rs12794714 is necessary to warrant proactive counseling and treatment against RSA.

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.

Dysregulation of vitamin D synthesis pathway genes in colorectal cancer: A case-control study

Background

The cytochromes P450 are a superfamily of enzymes that control the synthesis of the biologically active form of vitamin D, 1,25‐dihydroxyvitamin D3. These enzymes contribute to the formation of 1,25‐dihydroxyvitamin D3, which starts with a 25‐hydroxylation by CYP2R1 and CYP27A1 and a subsequent 1α‐hydroxylation via CYP27B1.

Methods

By using quantitative real‐time polymerase chain reaction (qRT‐PCR), we analyzed the expression ratio of CYP2R1, CYP27A1 and CYP27B1 genes within the vitamin D metabolic pathway in a total of 75 colorectal cancer (CRC) tissues compared to the adjacent tissues. Furthermore, we evaluated the association of CYP27B1 rs4646536 and CYP2R1 rs12794714 and rs10766196 polymorphisms with CRC risk in a total of 490 subjects, including 245 CRC patients and 245 non‐cancer controls. The genotyping was performed using tetra‐primer amplification refractory mutation system polymerase chain reaction (TP‐ARMS–PCR) method.

Results

The results indicated 2.3 and 2.7 upregulation of CYP2R1 and CYP27B1 genes in colorectal cancer tissues compared to the adjacent tissues, respectively. Rs12794714 AG genotype increased the risk of CRC (P = .03). Furthermore, a significant association was observed under the dominant inheritance model (P = .039).

Conclusion

CYP2R1 and CYP27B1 genes were over‐expressed in CRC samples compared to the adjacent control tissues. Furthermore, CYP2R1 rs12794714 variant was associated with the risk of CRC in the studied samples. CYP2R1 rs10766196 and CYP27B1 rs4646536 are not responsible for CYP2R1 and CYP27B1 genes expression alteration, respectively, but CYP2R1 rs12794714 polymorphism may be the reason of CYP2R1 upregulation and increased the risk of CRC.

Genetic variants of vitamin D metabolism-related DHCR7/NADSYN1 locus and CYP2R1 gene are associated with clinical features of Parkinson's disease

PURPOSE/AIM OF THE STUDY

Parkinson's disease (PD) is the second most common neurodegenerative disorder. Vitamin D deficiency is suggested to be related to PD. A genome-wide association study indicated that genes involved in vitamin D metabolism affect vitamin D levels. Among these genes, single nucleotide polymorphisms (SNPs) of the vitamin D receptor (VDR) and vitamin D binding protein (VDBP/GC) genes have also been demonstrated to be associated with PD risk. Our aim was to investigate the relevance of SNPs within the 7-dehydrocholesterol reductase/nicotinamide adenine dinucleotide synthetase 1 (DHCR7/NADSYN1) locus and vitamin D 25-hydroxylase (CYP2R1) gene, which encode important enzymes that play a role in the vitamin D synthesis pathway, with PD and its clinical features.

MATERIALS AND METHODS

Genotypes of 382 PD patients and 240 cognitively healthy individuals were evaluated by a LightSNiP assay for a total of 10 SNPs within the DHCR7/NADSYN1 locus and CYP2R1 gene.

RESULTS

There were no significant differences in the allele and genotype distributions of any of the SNPs between any patient groups and healthy subjects. However, our results indicated that all of the SNPs within the DHCR7/NADSYN1 locus and CYP2R1 gene, except rs1993116, were associated with clinical motor features of PD including initial predominant symptom, freezing of gait (FoG) and falls as well as disease stage and duration of the disease.

CONCLUSIONS

In conclusion, genetic variants of the DHCR7/NADSYN1 locus and the CYP2R1 gene might be related to the inefficient utilization of vitamin D independent from vitamin D levels, and it might result in differences in the clinical features of PD patients.

Obesity Represses CYP2R1, the Vitamin D 25-Hydroxylase, in the Liver and Extrahepatic Tissues

Low plasma level of 25-hydroxyvitamin D (25-OH-D), namely vitamin D deficiency, is associated with obesity and weight loss improves 25-OH-D status. However, the mechanism behind obesity-induced vitamin D deficiency remains unclear. Here, we report that obesity suppresses the expression of cytochrome P450 (CYP) 2R1, the main vitamin D 25-hydroxylase, in both mice and humans. In humans, weight loss induced by gastric bypass surgery increased the expression of CYP2R1 in the s.c. adipose tissue suggesting recovery after the obesity-induced suppression. At the same time, CYP27B1, the vitamin D 1α-hydroxylase, was repressed by the weight loss. In a mouse (C57BL/6N) model of diet-induced obesity, the plasma 25-OH-D was decreased. In accordance, the CYP2R1 expression was strongly repressed in the liver. Moreover, obesity repressed the expression of CYP2R1 in several extrahepatic tissues, the kidney, brown adipose tissue, and testis, but not in the white adipose tissue. Obesity had a similar effect in both male and female mice. In mice, obesity repressed expression of the vitamin D receptor in brown adipose tissue. Obesity also upregulated the expression of the vitamin D receptor and CYP24A1 in the s.c. adipose tissue of a subset of mice; however, no effect was observed in the human s.c. adipose tissue. In summary, we show that obesity affects CYP2R1 expression both in the mouse and human tissues. We suggest that in mouse the CYP2R1 repression in the liver plays an important role in obesity-induced vitamin D deficiency. Currently, it is unclear whether the CYP2R1 downregulation in extrahepatic tissues could contribute to the obesity-induced low plasma 25-OH-D, however, this phenomenon may affect at least the local 25-OH-D concentrations. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Prolonged 25-OH Vitamin D Deficiency Does Not Impair Bone Mineral Density in Adult Patients With Vitamin D 25-Hydroxylase Deficiency (CYP2R1)

Vitamin D-dependent rickets type 1B (VDDR1B) is an autosomal semidominant genetic disorder caused by a deficiency in CYP2R1, which encodes vitamin D 25-hydroxylase, an enzyme that plays a crucial role in the conversion of vitamin D to 25-dihydroxyvitamin D₃. VDDR1B is a severe form of rickets that occurs during infancy and which is responsive to 25-OH vitamin D supplementation. We studied three adult patients from a multi-consanguineous family with VDDR1B. They have been diagnosed with pseudo-nutritional rickets and treated during their adolescence with 25-OH vitamin D. These patients stopped their treatments at the end of adolescence and were contacted 14 to 17 years later when VDDR1B diagnosis was carried out in their niece and nephews. These three patients had undetectable 25-OH vitamin D, but normal levels of plasma 1-25(OH)₂ vitamin D. All patients had a hip bone mineral density and a normal vertebral despite osteoarthritis degenerative lesions which may impact BMD evaluation. These findings show that vitamin D supplementation has a questionable effect, if any, for osteoporosis prevention in adulthood in contrast to its crucial importance during infancy and adolescence.

Association study between genetic variants in vitamin D metabolism related genes and childhood autism spectrum disorder

Vitamin D deficiency has been implicated as a risk factor for autism spectrum disorder (ASD). This case-controlled study was to determine the association between single nucleotide polymorphisms (SNPs) in genes encoding vitamin D metabolism related enzymes and childhood ASD in a Chinese Han population. Both autistic children and age-and gender-matched healthy controls were recruited from September 2012-November 2017. The severity of ASD was evaluated by the childhood autism rating scale (CARS). Taqman probe based real-time PCR was applied to examine genotypes. The association between SNPs and the risk of ASD or the disease severity was examined through the logistic regression. This study recruited 249 children with ASD and 353 healthy controls. The G/A genotype (P = 0.0112) or the G allele (P = 0.0117) of CYP24A1 rs17219315, and the G/A genotype of CYP27B1 rs4646536 (P = 0.0341) were significantly associated with an increased risk of ASD. In addition, multivariate analysis found that A allele of both CYP2R1 rs12794714 (P = 0.0159) and CYP27B1 rs4646536 (P = 0.0268) were significantly associated with the severity of ASD. Genetic polymorphisms in vitamin D metabolism related enzymes are associated with the risk of childhood ASD and the severity of the disease.

Genetic polymorphisms in vitamin D pathway influence 25(OH)D levels and are associated with atopy and asthma

Background

Vitamin D deficiency or insufficiency, has been associated with atopy and lack of asthma control. Our objective was to investigate associations between variants in genes of vitamin D pathway with serum levels of 25-hydroxyvitamin D (25(OH)D), atopy, asthma and asthma severity in teenagers from Northeast Brazil.

Methods

This is a cross sectional study nested in a cohort population of asthma. 25(OH)D was quantified from 968 of 11–17 years old individuals by ELISA. Asthma diagnosis was obtained by using the ISAAC Phase III questionnaire. Specific IgE was determined by ImmunoCAP; genotyping was performed using the 2.5 HumanOmni Biochip from Illumina. Statistical analyses were performed in PLINK 1.07 and SPSS 22.1.

Results

After quality control, 104 Single Nucleotides Variants (SNVs) in vitamin D pathway genes, typed in 792 individuals, were included in the analysis. The allele A of rs10875694 on VDR was positively associated with atopy (OR = 1.35; 95% CI 1.01–1.81). The allele C of rs9279 on VDR, was negatively associated with asthma risk (OR = 0.66; 95% CI 0.45–0.97), vitamin D insufficiency (OR = 0.78; 95% CI 0.70–0.96) and higher VDR expression. Two variants in VDR were associated with asthma severity, the allele A of rs2189480 (OR = 0.34; 95% CI 0.13–0.89) and the allele G of rs4328262 (OR = 3.18; 95% CI 1.09–9.28). The combination of variants in CYP2R1 and CYP24A1 (GAC, to rs10500804, rs12794714 and rs3886163, respectively) was negatively associated with vitamin D production (β = − 1.24; 95% CI − 2.42 to − 0.06).

Conclusions

Genetic variants in the vitamin D pathway affect vitamin D serum levels and, thus, atopy and asthma.

Genetic variants of VDR and CYP2R1 affect BMI independently of serum vitamin D concentrations

BACKGROUND

Vitamin D metabolism and obesity have been linked by several studies, however the reason for this association is unclear. Our objective was to investigate potential correlations between genetic variants in key enzymes of vitamin D metabolism and the body mass index on a representative and random sample of Hungarian adults.

METHODS

Altogether 462 severely vitamin D deficient individuals were studied at the end of winter in order to decrease environmental and maximize any relevant genetic effect. Furthermore, participants with lifestyle factors known to affect vitamin D homeostasis were also excluded. We selected 23 target SNPs in five genes that encode key proteins of vitamin D metabolism (NADSYN1, GC, CYP24A1, CYP2R1, VDR).

RESULTS

Variants in 2 genetic polymorphisms; rs2853564 (VDR) and rs11023374 (CYP2R1) showed a significant association with participants' BMI. These associations survived further adjustment for total-, free-, or bioactive-25(OH) vitamin D levels, although the variance explained by these 2 SNPS in BMI heterogeneity was only 3.2%.

CONCLUSION

Our results show two novel examples of the relationship between genetics of vitamin D and BMI, highlighting the potential role of vitamin D hormone in the physiology of obesity.

CYP2R1 and CYP27A1 genes: An in silico approach to identify the deleterious mutations, impact on structure and their differential expression in disease conditions

Mutations in CYP2R1 and CYP27A1 involved in the conversion of Cholecalciferol into Calcidiol were associated with the impaired 25-hydroxylase activity therefore affecting the Vitamin D metabolism. Hence, this study attempted to understand the influence of genetic variations at the sequence and structural level via computational approach. The non-synonymous mutations retrieved from dbSNP database were assessed for their pathogenicity, stability as well as conservancy using various computational tools. The above analysis predicted 11/260 and 35/489 non-synonymous mutations to be deleterious in CYP2R1 and CYP27A1 genes respectively. Native and mutant forms of the corresponding proteins were modeled. Further, interacting native and mutant proteins with cholecalciferol showed difference in hydrogen bonds, hydrophobic bonds and their binding affinities suggesting the possible influence of these mutations in their function. Also, expression of these genes in various disease conditions was investigated using GEO datasets which predicted that there is a differential expression in cancer and arthritis.

Genes and metabolic pathway of sarcoidosis: identification of key players and risk modifiers

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.

Obesity Decreases Hepatic 25-Hydroxylase Activity Causing Low Serum 25-Hydroxyvitamin D

Normal vitamin D homeostasis is critical for optimal health; nevertheless, vitamin D deficiency is a worldwide public health problem. Vitamin D insufficiency is most commonly due to inadequate cutaneous synthesis of cholecalciferol and/or insufficient intake of vitamin D, but can also arise as a consequence of pathological states such as obesity. Serum concentrations of 25(OH)D (calcidiol) are low in obesity, and fail to increase appropriately after vitamin D supplementation. Although sequestration of vitamin D in adipose tissues or dilution of ingested or cutaneously synthesized vitamin D in the large fat mass of obese patients has been proposed to explain these findings, here we investigate the alternative mechanism that reduced capacity to convert parent vitamin D to 25(OH)D due to decreased expression of CYP2R1, the principal hepatic vitamin D 25-hydroxylase. To test this hypothesis, we isolated livers from female mice of 6 to 24 weeks of age, weaned onto either a normal chow diet or a high-fat diet, and determined the abundance of Cyp2r1 mRNA using digital droplet-quantitative PCR. We observed a significant (p < 0.001) decrease in Cyp2r1 mRNA in the liver of high-fat diet-fed mice relative to lean-chow-fed female mice. Moreover, there was a significant (p < 0.01) relationship between levels of Cyp2r1 mRNA and serum 25(OH)D concentrations as well as between Cyp2R1 mRNA and the ratio of circulating 25(OH)D3 to cholecalciferol (p < 0.0001). Using linear regression we determined a curve with 25(OH)D3/cholecalciferol versus normalized Cyp2R1 mRNA abundance with an R2 value of 0.85. Finally, we performed ex vivo activity assays of isolated livers and found that obese mice generated significantly less 25(OH)D3 than lean mice (p < 0.05). Our findings indicate that expression of CYP2R1 is reduced in obesity and accounts in part for the decreased circulating 25(OH)D. © 2019 American Society for Bone and Mineral Research.

A variant in CYP2R1 predicts circulating vitamin D levels after supplementation with high-dose of vitamin D in healthy adolescent girls

AIM

The determinants of serum vitamin D seems to be the environmental factors (dietary and supplementary intake and exposure to ultraviolet light) and genetic factors. We aimed to study the relationship between a vitamin D-associated genetic polymorphism and serum 25(OH)D concentrations in healthy adolescent girls in Iran, and its effects on a high-dose supplement of vitamin D.

MATERIAL AND METHOD

A total of 616 healthy adolescent girls with mean age 15 received 50,000 IU of vitamin D3 weekly over 9 weeks. Serum vitamin D levels and other metabolic factors were measured at baseline and after the intervention. The genotyping of the CYP2R1 variant (rs10741657) was performed by TaqMan genotyping assays.

RESULTS

Regardless of the genetic background, at baseline, 87% of adolescent girls were vitamin D deficient (serum 25(OH)D level < 50 nmol/l). High-dose supplementation with VitD reduced the proportion of girls who were deficient substantially to about 24%. The genetic analysis revealed that although at baseline there was not a gene-vitamin D association ( p trend = 0.1), the response to supplementation appeared to be modulated by this variant ( p trend < 0.001). However, other anthropometric and biochemical measures were not affected by this intervention, over this short period. Serum 25(OH)D was increased in all participants although the carriers of the minor A allele seemed to be better responders so that the percentages of the change serum vitamin D in the holder of AA and AG genotypes were 539.4 ± 443.1 and 443.7 ± 384.6, respectively, compared with those with common GG genotype (363.3 ± 354.0). Our regression analysis revealed that the probability of an increase in serum 25(OH)D in a participant with AA genotype was 2.5-fold greater than those with a GG genotype (OR = 2.5 (1.4-4.4); p value = 0.002).

CONCLUSION

Based on our findings, it appears that the rs10741657 variant of the CYP2R1 gene modulates the response to high-dose of vitamin D supplementation.

Effects of CYP2R1 gene variants on vitamin D levels and status: A systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

CYP2R1 is a key gene in the vitamin D metabolic pathway. It has been suggested that CYP2R1 gene variants in European populations are associated with concentrations of 25(OH)D, a biomarker of vitamin D levels and status in peripheral blood. However, a comprehensive meta-analysis of this effect including different ethnicities has never been conducted. The objective of this meta-analysis was to evaluate the association between CYP2R1 gene variants and 25(OH)D levels and vitamin D status.

METHODS

PubMed, EMBASE, Web of Science, CNKI and Wanfang databases were systematically searched up to May 2018. Reporting followed PRISMA guidelines. The quality of the evidence was assessed using the STREGA system. Random or fixed effects model combined estimates and sub-group tested for ethnic differences. The I² statistic quantified between-study variation due to heterogeneity.

RESULTS

Sixteen articles with a total of 52,417 participants met the inclusion criteria and were included in the meta-analysis. For rs10741657, GG genotype was associated with a clear descending trend of 25(OH)D levels when compared with the AA genotype [SMD = -2.32, 95% CI (-4.42, -0.20); SMD = -3.46, 95% CI (-6.60, -0.33) and SMD = -0.24, 95% CI (-0.51, -0.03) for total, Caucasian and Asian groups, respectively] with the following heterogeneities I² = 37.9%, 69.2% and 24.5%, respectively. However, under the AG/AA genetic model, significant changes in 25(OH)D levels [SMD and 95% CI: -1.27(-2.32, -0.23)] were only evident in the Caucasian population. The meta-analysis on vitamin D deficiency showed that the risk-allele G was associated with an increased risk of vitamin D deficiency (OR = 1.09; 95% CI = 1.03-1.15, P = 0.002). The association between rs10741657 and increased risk of vitamin D deficiency was significant (OR = 1.42; 95% CI = 1.11-1.83, P = 0.006) under the dominant model (GG + AG/AA), but not under the recessive model (GG/AG + AA), (OR = 1.28; 95% CI = 0.89-1.84, P = 0.181). There was no evidence of publication bias.

CONCLUSION

Published articles provide evidence supporting a major role for the rs10741657 polymorphism of the CYP2R1 gene in determining 25(OH)D levels and the presence of vitamin D deficiency.

Triangular relationship between CYP2R1 gene polymorphism, serum 25(OH)D3 levels and T2DM in a Chinese rural population

BACKGROUND

A low serum vitamin D concentration is associated with an increased risk of type 2 diabetes mellitus (T2DM). Recently, several single nucleotid polymorphisms (SNPs) have been identified which influence vitamin D levels. If a causal relationship exists between vitamin D concentrations and T2DM, one would expect a similar association between the newly identified SNPs and T2DM risk. Therefore, this study investigated the association between four SNPs of cytochrome P450 family 2, subfamily R, peptide 1 (CYP2R1) gene, serum 25(OH)D₃ levels and T2DM.

METHODS

Three hundred and ninety-seven patients with confirmed T2DM, as well as 397 age- and gender-matched controls were enrolled in this case-control study. Genotyping was performed by TaqMan probe assays. Kruskal-Wallis one-way analysis and muitiple logistic regression analysis were performed to identify the possible risk genotype for vitamin D levels and T2DM, respectively. Generalized multifactor dimensionality reduction (GMDR) was used to analyze the gene-gene and gene-environment interactions.

RESULTS

The serum 25(OH)D₃ levels were significant lower in the T2DM group. Significant differences were observed between patients and controls in terms of the genotype distributions of rs1993116 (P = 0.048) and rs10766197 (P = 0.024). Similarly, rs1993116 and rs10766197 polymorphisms were found to be significantly associated with T2DM risk. AG + GG genotype carriers of the rs1993116 and rs10766197 polymorphisms could have an increased risk of developing T2DM compared with AA carriers, the OR and 95% CI were 1.64 (1.09-2.46) and 1.76 (1.18-2.65), respectively. However, none of the tested SNPs were independently associated with serum 25(OH)D₃ levels (P > 0.059). Gene-gene and gene-environment interaction analyses indicated that rs12794714-rs10766197 and rs12794714-vitamin D deficiency (VDD) models successfully predicted T2DM risk (P < 0.001).

CONCLUSIONS

Rs1993116 and rs10766197 polymorphisms of CYP2R1 gene may be novel genetic markers for T2DM in China. Given the lack of association between SNPs and serum 25(OH)D₃ levels, well-designed future studies should be conducted with larger sample sizes in rural areas of China.

The genetic determinants of circulating C3-epimers of 25-hydroxyvitamin D

BACKGROUND

The complexity of vitamin D metabolites especially the contribution of C3-epimers of 25-hydroxyvitamin D (C3-epimers) in human sera remains unclear. We hypothesized that genetic polymorphisms in the vitamin D-related gene pathway contribute to variation in C3-epimer levels. Therefore, we investigated candidate single nucleotide polymorphisms (SNPs) concerning C3-epimer levels.

METHODS

The candidate SNPs, including DHCR7/NADSYN1 (rs12785878), CYP2R1 (rs2060793) and GC (rs2282679), were genotyped in 1727 members of the third project of the Electricity Generating Authority of Thailand 3/1 cohort investigation. Each SNP was tested under three genetic effects (dominant, recessive and additive models) concerning the levels of total serum 25(OH)D [the sum of 25(OH)D2+3 and 3-epi-25(OH)D2+3], non-C3-epimers [25(OH)D2+3] and C3-epimers [3-epi-25(OH)D2+3], using linear regression analysis.

RESULTS

Among the participants, the median (range) levels of non-C3-epimers and C3-epimers were 22.7 (6.4-49.2) ng/mL and 1.3 (0.01-14.2) ng/mL, respectively. In regression analysis, we found the genetic variation of two SNPs, the DHCR7/NADSYN1 (rs12785878; G > T) and GC (rs2282679; T > G) under additive genetic models, explained the variation of C3-epimer levels about 1.5% (p = 1.66 × 10-7) and 1.1% (p = 1.10 × 10-5), respectively. Interestingly, participants carrying the minor T-allele of rs12785878 exhibited a trend to increase C3-epimer levels, while those carrying the minor G-allele of rs2282679 exhibited a trend to decrease levels of both non-C3-epimers and C3-epimers. In addition, CYP2R1 (rs2060793; G > A) was clearly associated only with non-C3-epimer levels (p = 2.46 × 10-8). In multivariate analyses, sex, age and BMI were predictors for variation in C3-epimer concentration; sex and age for variation in non-C3-epimers.

CONCLUSION

To the best of our knowledge, this is the first study to demonstrate genetic models concerning the variation in C3-epimer levels. Our results emphasize that genetic determinants and the potential factors of C3-epimers differ from non-C3-epimers. This study contributes fundamental knowledge of the endogenous vitamin D pathway.