GC and VDR SNPs and Vitamin D Levels in Parkinson’s Disease: The Relevance to Clinical Features

Impact of body mass index elevation, Vitamin D receptor polymorphisms and antipsychotics on the risk of Vitamin D deficiency in schizophrenia patients

Antipsychotics with weight gain as side effect and vitamin D receptor dysfunction associated with single nucleotide polymorphisms (VDR SNPs) may have different effects on vitamin D status. Hence, present study aimed to investigate the relationship between vitamin D with body mass index (BMI), antipsychotics and VDR SNPs (rs2228570, rs1544410, rs7975232 and rs731236) in Malaysian patients with schizophrenia. Serum vitamin D level was measured using competitive enzyme-linked immunosorbent assay kit. VDR SNPs were analyzed using polymerase chain reaction-restriction fragment length polymorphism. We found significantly lower serum vitamin D level in patients with schizophrenia (p < 0.01), especially those taking atypical antipsychotics (p = 0.02) and combined antipsychotics (p = 0.02) and obese (BMI ≥27.5 kg/m2) patients (p = 0.04) after adjustment for covariates. For VDR SNPs, the CT genotype of rs1544410, CA genotype of rs7975232, and AA and AG genotypes of rs731236 may contribute to the significant decreased serum vitamin D level in patients (p < 0.05). Nevertheless, these relationships may differ by populations or medical conditions. The hypotheses of volumetric dilution and sequestration of vitamin D may explain the lower vitamin D level in obese patients. In addition, lifestyle factors such as poor diet and lack of physical activity with less sunlight exposure may cause reduced vitamin D level among patients. As patients in present study were prescribed with various antipsychotics, the effect of each antipsychotic on vitamin D level could not be determined. Thus, future studies should investigate the effect of different types of antipsychotics and obesity on vitamin D level in schizophrenia.

Role of Calcitriol and Vitamin D Receptor (VDR) Gene Polymorphisms in Alzheimer's Disease

Alzheimer's disease (AD) is characterized by amyloid beta (Aβ) buildup and neuronal degeneration. An association between low serum vitamin D levels and an increased risk of AD has been reported in several epidemiological studies. Calcitriol (1,25-dihydroxycholecalciferol) is the active form of vitamin D, and is generated in the kidney and many other tissues/organs, including the brain. It is a steroid hormone that regulates important functions like calcium/phosphorous levels, bone mineralization, and immunomodulation, indicating its broader systemic significance. In addition, calcitriol confers neuroprotection by mitigating oxidative stress and neuroinflammation, promoting the clearance of Aβ, myelin formation, neurogenesis, neurotransmission, and autophagy. The receptors to which calcitriol binds (vitamin D receptors; VDRs) to exert its effects are distributed over many organs and tissues, representing other significant roles of calcitriol beyond sustaining bone health. The biological effects of calcitriol are manifested through genomic (classical) and non-genomic actions through different pathways. The first is a slow genomic effect involving nuclear VDR directly affecting gene transcription. The association of AD with VDR gene polymorphisms relies on the changes in vitamin D consumption, which lowers VDR expression, protein stability, and binding affinity. It leads to the altered expression of genes involved in the neuroprotective effects of calcitriol. This review summarizes the neuroprotective mechanism of calcitriol and the role of VDR polymorphisms in AD, and might help develop potential therapeutic strategies and markers for AD in the future.

Associations of vitamin D receptor polymorphisms with risk of Alzheimer's disease, Parkinson's disease, and mild cognitive impairment: a systematic review and meta-analysis

Vitamin D is a lipid soluble steroid hormone, which plays a critical role in the calcium homeostasis, neuronal development, cellular differentiation, and growth by binding to vitamin D receptor (VDR). Associations between VDR gene polymorphism and Alzheimer's disease (AD), Parkinson's disease (PD), and mild cognitive impairment (MCI) risk has been investigated extensively, but the results remain ambiguous. The aim of this study was to comprehensively assess the correlations between four VDR polymorphisms (FokI, BsmI, TaqI, and ApaI) and susceptibility to AD, PD, and MCI. Crude odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to determine the relationship of interest. Pooled analyses suggested that the ApaI polymorphism decreased the overall AD risk, and the TaqI increased the overall PD susceptibility. In addition, the BsmI and ApaI polymorphisms were significantly correlated with the overall MCI risk. Stratified analysis by ethnicity further showed that the TaqI and ApaI genotypes reduced the AD predisposition among Caucasians, while the TaqI polymorphism enhanced the PD risk among Asians. Intriguingly, carriers with the BB genotype significantly decreased the MCI risk in Asian descents, and the ApaI variant elevated the predisposition to MCI in Caucasians and Asians. Further studies are need to identify the role of VDR polymorphisms in AD, PD, and MCI susceptibility.

Vitamin D Receptor Polymorphisms in a Spanish Cohort of Parkinson's Disease Patients

Background: Vitamin D receptor (VDR) is a nuclear hormone receptor widely expressed in the substantia nigra. Its association with an increased risk of Parkinson's disease (PD) is based on vitamin D deficiency and/or different polymorphisms in its gene receptor. This fact has been demonstrated by several case-control studies. Materials and Methods: Consequently, we investigated the association between VDR ApaI, BsmI, FokI, and TaqI gene polymorphisms and PD in a Spanish cohort that included 54 cases and 17 healthy controls. The detection of single nucleotide polymorphisms (SNPs) was performed using a polymerase chain reaction-restriction fragment length polymorphism. Results: Our data indicate that the SNPs were not associated with the age of onset of PD, nor with the occurrence of motor symptoms. However, only BsmI polymorphism was significantly associated with PD in this Spanish cohort. In fact, BsmI genotype was five times higher among PD patients than among controls, and the A allele was considered as a genetic risk for PD. Additionally, the combination of FokI and BsmI polymorphisms was significantly associated with PD and could represent a risk factor. Conclusion: We conclude that ApaI, TaqI, and FokI polymorphisms were not associated with PD, but BsmI could be a risk factor for PD in this randomized population.

Association of Vitamin D Levels with Risk of Cognitive Impairment and Dementia: A Systematic Review and Meta-Analysis of Prospective Studies

Background

Emerging evidence suggests the potential relationship between vitamin D deficiency and risk of cognitive impairment or dementia. To what extent the excess risk of dementia conferred by vitamin D deficiency is less clear.

Objective

We summarized the current evidence from several aspects and further quantified these associations.

Methods

We collected relevant prospective cohort studies by searching PubMed, Embase and Cochrane up to July 2023. The pooled relative risks (RR) were evaluated by random-effects models. Dose-response analyses were conducted by the method of two-stage generalized least squares regression.

Results

Of 9,267 identified literatures, 23 were eligible for inclusion in the meta-analyses, among which 9 and 4 literatures were included in the dose-response analyses for the risk of dementia and Alzheimer's disease (AD). Vitamin D deficiency exhibited a 1.42 times risk for dementia (95% confidence interval (CI) = 1.21-1.65) and a 1.57-fold excess risk for AD (95% CI = 1.15-2.14). And vitamin D deficiency was associated with 34% elevated risk with cognitive impairment (95% CI = 1.19-1.52). Additionally, vitamin D was non-linearly related to the risk of dementia (pnonlinearity = 0.0000) and AD (pnonlinearity = 0.0042). The approximate 77.5-100 nmol/L 25-hydroxyvitamin D [25(OH)D] was optimal for reducing dementia risk. And the AD risk seemed to be decreased when the 25(OH)D level >40.1 nmol/L.

Conclusions

Vitamin D deficiency was a risk factor for dementia, AD, and cognitive impairment. The nonlinear relationships may further provide the optimum dose of 25(OH)D for dementia prevention.

Vitamin D deficiency and genetic polymorphisms of vitamin D-associated genes in Parkinson's disease

Parkinson's disease (PD) and vitamin D share a unique link as vitamin D deficiency (VDD) prevails in PD. Thus, an in-depth understanding of vitamin D biology in PD might be crucial for therapeutic strategies emphasising vitamin D. Specifically, explicating the effect of VDD and genetic polymorphisms of vitamin D-associated genes in PD, like VDR (vitamin D receptor) or GC (vitamin D binding protein) may aid the process along with polymorphisms of vitamin D metabolising genes (e.g., CYP2R1 and CYP27A1) in PD. Literature review of single nucleotide polymorphisms (SNPs) related to vitamin D levels [GC (GC1-rs7041 and GC2-rs4588), CYP2R1, CYP24A1 and CYP27B1] and vitamin D function [VDR (FokI - rs2228570 and rs10735810; ApaI - rs7976091, rs7975232BsmI and rs1544410; and TaqI - rs731236)] was conducted to explore their relationship with PD severity globally. VDR-FokI polymorphism was reported to be significantly associated with PD in Hungarian, Chinese and Japanese populations, whereas VDR-ApaI polymorphism was found to affect PD in the Iranian population. However, VDR-TaqI and BsmI polymorphisms had no significant association with PD severity. Conversely, GC1 polymorphisms reportedly affected vitamin D levels without influencing the disease severity. CYP2R1 (excluding rs1993116) was also reportedly linked to clinical manifestations of PD. Genetic polymorphisms might cause VDD despite enough sunlight exposure and vitamin D-rich food intake, enhancing inflammation, there by influencing PD pathophysiology. Knowledge of the polymorphisms associated with VDD appears promising for developing precision vitamin D-dosing therapeutic strategies against PD.

Vitamin D receptor regulates transcription of mitochondrial DNA and directly interacts with mitochondrial DNA and TFAM

Vitamin D receptor (VDR) is an essential transcription factor (TF) synthesized in different cell types. We hypothesized that VDR might also act as a mitochondrial TF. We conducted the experiments in primary cortical neurons, PC12, HEK293T, SH-SY5Y cell lines, human peripheral blood mononuclear cells (PBMC) and human brain. We showed that vitamin D/VDR affects the expression of mitochondrial DNA (mtDNA) encoded oxidative phosphorylation (OXPHOS) subunits. We observed the co-localization of VDR with mitochondria and the mtDNA with confocal microscopy. mtDNA-chromatin-immunoprecipitation and electrophoretic mobility shift assays indicated that VDR was able to bind to the mtDNA D-loop site in several locations, with a consensus sequence 'MMHKCA'. We also reported the possible interaction between VDR and mitochondrial transcription factor A (TFAM) and their binding sites located in close proximity in mtDNA. Consequently, our results showed for the first time that VDR was able to bind and regulate mtDNA transcription and interact with TFAM even in the human brain. These results not only revealed a novel function of VDR, but also showed that VDR is indispensable for energy demanded cells.

Vitamin D, a Secosteroid Hormone and Its Multifunctional Receptor, Vitamin D Receptor, in Alzheimer's Type Neurodegeneration

Vitamin D is a secosteroid hormone exerting neurosteroid-like properties. Its well-known nuclear hormone receptor, and recently proposed as a mitochondrial transcription factor, vitamin D receptor, acts for its primary functions. The second receptor is an endoplasmic reticulum protein, protein disulfide isomerase A3 (PDIA3), suggested to act as a rapid response. Vitamin D has effects on various systems, particularly through calcium metabolism. Among them, the nervous system has an important place in the context of our subject. Recent studies have shown that vitamin D and its receptors have numerous effects on the nervous system. Neurodegeneration is a long-term process. Throughout a human life span, so is vitamin D deficiency. Our previous studies and others have suggested that the out-come of long-term vitamin D deficiency (hypovitaminosis D or inefficient utilization of vitamin D), may lead neurons to be vulnerable to aging and neurodegeneration. We suggest that keeping vitamin D levels at adequate levels at all stages of life, considering new approaches such as agonists that can activate vitamin D receptors, and utilizing other derivatives produced in the synthesis process with UVB are crucial when considering vitamin D-based intervention studies. Given most aspects of vitamin D, this review outlines how vitamin D and its receptors work and are involved in neurodegeneration, emphasizing Alzheimer's disease.

Vitamin D Receptor and Binding Protein Gene Variants in Patients with Essential Tremor

Several studies have shown an association between some variants in the vitamin D receptor (VDR) and the GC vitamin D binding protein (GC) genes with the risk for Parkinson's disease or other neurological disorders. VDR rs2228570 has shown an association with essential tremor (ET) in a previous study. The aim of this study is to look for the association between several common variants in these genes and the risk for ET. We genotyped 272 patients diagnosed with familial ET and 272 age-matched controls using specific TaqMan assays for VDR rs2228570, VDR rs731236, VDR rs7975232, VDR rs739837, VDR rs78783628, GC rs7041, and GC rs4588 single nucleotide variants (SNVs). We found an association between GC rs7041 SNV and ET using recessive, codominant, and allelic models. Despite our results did not find an association between VDR rs2228570 and ET, the pooled data with those by a previous report suggest this association under recessive, codominant, and allelic models. None of the SNVs studied was related to the age at onset of tremor in ET patients. Data from the current study suggest an association between GC rs7041 and VDR rs2228570 SNVs and ET risk.

Vitamin D and Parkinson's Disease

Vitamin D is a fat-soluble secosteroid, traditionally considered a key regulator of bone metabolism, calcium and phosphorous homeostasis. Its action is made possible through the binding to the vitamin D receptor (VDR), after which it directly and indirectly modulates the expression of thousands of genes. Vitamin D is important for brain development, mature brain activity and associated with many neurological diseases, including Parkinson’s disease (PD). High frequency of vitamin D deficiency in patients with Parkinson’s disease compared to control population was noted nearly twenty years ago. This finding is of interest given vitamin D’s neuroprotective effect, exerted by the action of neurotrophic factors, regulation of nerve growth or through protection against cytotoxicity. Vitamin D deficiency seems to be related to disease severity and disease progression, evaluated by Unified Parkinson’s Disease Rating Scale (UPDRS) and Hoehn and Yahr (H&Y) scale, but not with age of PD onset and duration of disease. Additionally, fall risk has been associated with lower vitamin D levels in PD. However, while the association between vitamin D and motor-symptoms seems to be possible, results of studies investigating the association with non-motor symptoms are conflicting. In addition, very little evidence exists regarding the possibility to use vitamin D supplementation to reduce clinical manifestations and disability in patients with PD. However, considering the positive balance between potential benefits against its limited risks, vitamin D supplementation for PD patients will probably be considered in the near future, if further confirmed in clinical studies.

rs7041 and rs4588 Polymorphisms in Vitamin D Binding Protein Gene (VDBP) and the Risk of Diseases

The purpose of the study was to investigate the role of vitamin D binding protein (VDBP, DBP) and its polymorphism in the vitamin D pathway and human health. This narrative review shows the latest literature on the most popular diseases that have previously been linked to VDBP. Vitamin D plays a crucial role in human metabolism, controlling phosphorus and calcium homeostasis. Vitamin D binding protein bonds vitamin D and its metabolites and transports them to target tissues. The most common polymorphisms in the VDBP gene are rs4588 and rs7041, which are located in exon 11 in domain III of the VDBP gene. rs4588 and rs7041 may be correlated with differences not only in vitamin D status in serum but also with vitamin D metabolites. This review supports the role of single nucleotide polymorphisms (SNPs) in the VDBP gene and presents the latest data showing correlations between VDBP variants with important human diseases such as obesity, diabetes mellitus, tuberculosis, chronic obstructive pulmonary disease, and others. In this review, we aim to systematize the knowledge regarding the occurrence of diseases and their relationship with vitamin D deficiencies, which may be caused by polymorphisms in the VDBP gene. Further research is required on the possible influence of SNPs, modifications in the structure of the binding protein, and their influence on the organism. It is also important to mention that most studies do not have a specific time of year to measure accurate vitamin D metabolite levels, which can be misleading in conclusions due to the seasonal nature of vitamin D.

Vitamin D receptor gene polymorphisms and idiopathic Parkinson disease: an Egyptian study

Background

Accumulating data have suggested that vitamin D receptor (VDR) gene is a pretender gene for vulnerability to Parkinson disease (PD). This study aimed to assess the relationship of VDR gene polymorphisms (FokI and ApaI) with PD. Fifty patients suffering from PD and 50 age- and sex-matched healthy controls were included. Unified Parkinson Disease Rating Scale (UPDRS) was done to assess disease severity. Genetic testing for VDR gene single nucleotide polymorphisms (FokI and ApaI) was done using real time polymerase chain reaction (PCR) technique.

Results

Concerning frequency of genes and alleles for vitamin D receptor gene polymorphisms (FokI and ApaI), no statistically significant difference was found between PD patients and controls. AC genotype was associated with younger age and younger age at onset of disease compared to CC and AA genotypes of ApaI gene polymorphisms. CC genotype was significantly positively correlated with fatigue and urine incontinence. VDR gene polymorphisms were not found to be independent predictors for severity of PD after adjustment for possible confounders.

Conclusion

VDR gene polymorphisms are related to the clinical manifestations rather than etiology or severity of idiopathic PD.

VDR Gene Polymorphisms and Cluster Headache Susceptibility: Case-Control Study in a Southeastern European Caucasian Population

Cluster headache (CH) is a severe primary headache disorder with a genetic component, as indicated by family and twin studies. Diurnal and seasonal rhythmicity are key features of the disease and might be related to vitamin D, as low vitamin D levels have been observed in patients with cluster headache. In addition, the vitamin D receptor (VDR) occurs in brain areas and particularly in the hypothalamus. The aim of the present case-control study was to investigate the association of cluster headache susceptibility and clinical phenotypes with the VDR gene polymorphisms FokI, BsmI and TaqI in a Southeastern European Caucasian population. DNA was extracted from 131 unrelated CH patients and 282 non-headache controls and genotyped using real-time PCR (melting curve analysis). Linkage disequilibrium (LD) analysis confirmed that BsmI and TaqI, both located in the 3'UTR of the VDR gene, are in strong LD. Genotype and allele frequency distribution analysis of the VDR FokI, BsmI, and TaqI polymorphisms showed no statistically significant difference between cases and controls, whereas haplotype analysis indicated that the TAC haplotype might be associated with decreased cluster headache susceptibility. Intra-patient analysis according to diverse clinical phenotypes showed an association of the BsmI GG and TaqI TT genotypes with more frequent occurrence of CH attacks in this cohort. Therefore, a possible association was observed between VDR gene polymorphisms BsmI and TaqI or a linked locus and susceptibility for cluster headache development and altered clinical phenotypes in the Southeastern European Caucasian study population. Further large-scale replication studies are needed to validate these findings.

Investigating the Role of Functional Polymorphism of Maternal and Neonatal Vitamin D Binding Protein in the Context of 25-Hydroxyvitamin D Cutoffs as Determinants of Maternal-Neonatal Vitamin D Status Profiles in a Sunny Mediterranean Region

Recent results indicate that dysregulation of vitamin D-binding protein (VDBP) could be involved in the development of hypovitaminosis D, and it comprises a risk factor for adverse fetal, maternal and neonatal outcomes. Until recently, there was a paucity of results regarding the effect of maternal and neonatal VDBP polymorphisms on vitamin D status during pregnancy in the Mediterranean region, with a high prevalence of hypovitaminosis D. We aimed to evaluate the combined effect of maternal and neonatal VDBP polymorphisms and different maternal and neonatal 25-hydroxyvitamin D (25(OH)D) cut-offs on maternal and neonatal vitamin D profile. Blood samples were obtained from a cohort of 66 mother–child pairs at birth. Our results revealed that: (i) Maternal VDBP polymorphisms do not affect neonatal vitamin D status at birth, in any given internationally adopted maternal or neonatal cut-off for 25(OH)D concentrations; (ii) neonatal VDBP polymorphisms are not implicated in the regulation of neonatal vitamin D status at birth; (iii) comparing the distributions of maternal VDBP polymorphisms and maternal 25(OH)D concentrations, with cut-offs at birth, revealed that mothers with a CC genotype for rs2298850 and a CC genotype for rs4588 tended to demonstrate higher 25(OH)D (≥75 nmol/L) during delivery (p = 0.05 and p = 0.04, respectively), after adjustments for biofactors that affect vitamin D equilibrium, including UVB, BMI and weeks of gestation. In conclusion, this study from Southern Europe indicates that maternal and neonatal VDBP polymorphisms do not affect neonatal vitamin D status at birth, whereas mothers with CC genotype for rs2298850 and CC genotype for rs4588 demonstrate higher 25(OH)D concentrations. Future larger studies are required to establish a causative effect of these specific polymorphisms in the attainment of an adequate (≥75 nmol/L) maternal vitamin D status during pregnancy.

The VDR FokI (rs2228570) polymorphism is involved in Parkinson's disease

The etiology of Parkinson's disease (PD) is presumably multifactorial and likely involves interactions between genetic and environmental factors, as well as mitochondrial dysfunction, oxidative stress and inflammation. Among environmental factors, Vitamin D was reported to associate with the risk of PD. Vitamin D activity is mediated by its binding to the vitamin D Receptor (VDR), a transcriptional factor for almost 3% of human genes. We genotyped for ApaI, BsmI, TaqI, FokI and rs1989969 VDR single nucleotide polymorphisms (SNPs) a cohort of 406 PD and 800 healthy controls (HC) and found a strong association between the FokI (rs2228570) VDR SNP and PD. Thus, the TT genotype and the T allele resulted associated with PD in the overall analyzed PD population. Gender-based stratification of data indicated that results were maintained for FokI TT genotype and T allele in male PD patients, whereas the FokI T allele alone was confirmed as a risk factor for PD in females. Co-segregation analyses indicated the TaqI ApaI FokI rs1989969 GCTG as a "risk" haplotype for PD. In a subgroup of patients and controls neural Vitamin D and VDR concentration was analyzed in extravesicles (NDEVs) isolated from peripheral blood: no differences emerged between PD and HC. NDEVs results will need to be validated in ampler cohort but we can speculate that, if at neuronal level the amounts of Vitamin D and of VDR are comparable, than the bioavailability of vitamin D and the efficacy of the vitamin D/VDR axis is differentially modulated in PD by VDR SNPs.

Association of Vitamin D Receptor Polymorphisms with Amyloid-β Transporters Expression and Risk of Mild Cognitive Impairment in a Chilean Cohort

Background: Amyloid-β peptide (Aβ) deposition in Alzheimer’s disease (AD) is due to an imbalance in its production/clearance rate. Aβ is transported across the blood-brain barrier by LRP1 and P-gp as efflux transporters and RAGE as influx transporter. Vitamin D deficit and polymorphisms of the vitamin D receptor (VDR) gene are associated with high prevalence of mild cognitive impairment (MCI) and AD. Further, vitamin D promotes the expression of LRP1 and P-gp in AD-animal model brains. Objective: To associate VDR polymorphisms Apa I (rs7975232), Taq I (rs731236), and Fok I (rs2228570) with the risk of developing MCI in a Chilean population, and to evaluate the relationship of these polymorphisms to the expression of VDR and Aβ-transporters in peripheral blood mononuclear cells (PBMCs). Methods: VDR polymorphisms Apa I, Taq I, and Fok I were determined in 128 healthy controls (HC) and 66 MCI patients. mRNA levels of VDR and Aβ-transporters were evaluated in subgroups by qPCR. Results: Alleles A of Apa I and C of Taq I were associated with a lower risk of MCI. HC with the Apa I AA genotype had higher mRNA levels of P-gp and LRP1, while the expression of VDR and RAGE were higher in MCI patients and HC. For Fok I, the TC genotype was associated with lower expression levels of Aβ-transporters in both groups. Conclusion: We propose that the response to vitamin D treatment will depend on VDR polymorphisms, being more efficient in carriers of protective alleles of Apa I polymorphism.

Altered Transcriptional Profile of Mitochondrial DNA-Encoded OXPHOS Subunits, Mitochondria Quality Control Genes, and Intracellular ATP Levels in Blood Samples of Patients with Parkinson's Disease

Mitochondrial dysfunctions are significant contributors to neurodegeneration. One result or a cause of mitochondrial dysfunction might be the disruption of mtDNA transcription. Limited data indicated an altered expression of mtDNA encoded transcripts in Alzheimer's disease (AD) or Parkinson's disease (PD). The number of mitochondria is high in cells with a high energy demand, such as muscle or nerve cells. AD or PD involves increased risk of cardiomyopathy, suggesting that mitochondrial dysfunction might be systemic. If it is systemic, we should observe it in different cell types. Given that, we wanted to investigate any disruption in the regulation of mtDNA encoded gene expression in addition to PINK1, PARKIN, and ATP levels in peripheral blood samples of PD cases who are affected by a neurodegenerative disorder that is very well known by its mitochondrial aspects. Our results showed for the first time that: 1) age of onset > 50 PD sporadic (PDS) cases: mtDNA transcription and quality control genes were affected; 2) age of onset <50 PDS cases: only mtDNA transcription was affected; and 3) PD cases with familial background: only quality control genes were affected. mtDNA copy number was not a confounder. Intracellular ATP levels of PD case subgroups were significantly higher than those of healthy subjects. We suggest that a systemic dysregulation of transcription of mtDNA or mitochondrial quality control genes might result in the development of a sporadic form of the disease. Additionally, ATP elevation might be an independent compensatory and response mechanism. Hyperactive cells in AD and PD require further investigation.

Diverse Effects of Combinations of Maternal-Neonatal VDR Polymorphisms and 25-Hydroxyvitamin D Concentrations on Neonatal Birth Anthropometry: Functional Phenocopy Variability Dependence, Highlights the Need for Targeted Maternal 25-Hydroxyvitamin D Cut-Offs during Pregnancy

Vitamin D receptor (VDR) polymorphisms have been associated with a plethora of adverse pregnancy and offspring outcomes. The aim of this study was to evaluate the combined effect of maternal and neonatal VDR polymorphisms (ApaI, TaqI, BsmI, FokI, Tru9I) and different maternal and neonatal 25(OH)D cut-offs on neonatal birth anthropometry. This cross-sectional study included data and samples from a cohort of mother–child pairs at birth. A detailed neonatal anthropometry analysis at birth was also conducted. Different 25(OH)D cut-offs for neonates and mothers were included, according to their vitamin D status at birth: for neonates, cut-offs of [25(OH)D ≤ 25 and > 25 nmol/L] and [25(OH)D ≤ 50 nmol/L] were adopted, whereas for mothers, a 25(OH)D cut-off of [25(OH)D ≤ 50 and > 50 nmol/L)] was investigated. Following this classification, maternal and neonatal VDR polymorphisms were evaluated to investigate the potential different effects of different neonatal and maternal 25(OH)D cut-offs on neonatal birth anthropometry. A total of 69 maternal-neonatal dyads were included in final analysis. Weight, neck rump length, chest circumference, abdominal circumference, abdominal circumference (iliac), high thigh circumference, middle thigh circumference, lower arm radial circumference, and lower leg calf circumference of neonates who had the TAQl SNP TT genotype and maternal 25(OH)D < 50 nmol/L were significantly higher than that of neonates who had the Tt or tt genotypes (p = 0.001, Hg = 1.341, p = 0.036, Hg = 0.976, p = 0.004, Hg = 1.381, p = 0.001, Hg = 1.554, p = 0.001, Hg = 1.351, p = 0.028, Hg = 0.918, p = 0.008, Hg = 1.090, p = 0.002, Hg = 1.217, and p = 0.020, Hg = 1.263, respectively). Skin fold high anterior was significantly lower in neonates who had the BSMI SNP BB genotype compared to that of neonates with Bb or bb genotypes (p = 0.041, Hg = 0.950), whereas neck rump length was significantly higher in neonates who had the FOKI SNP FF genotype compared to that of neonates who had Ff or ff genotypes (p = 0.042, Hg = 1.228). Regarding neonatal VDR polymorphisms and cut-offs, the abdominal circumference (cm) of neonates who had the TAQI SNP TT genotype and 25(OH)D < 25 nmol/L were significantly higher than that of neonates who had the Tt or tt genotypes (p = 0.038, Hg = 1.138). In conclusion, these results indicate that the maternal TAQI VDR polymorphism significantly affected neonatal birth anthropometry when maternal 25(OH) concentrations were <50 nmol/L, but not for a higher cut-off of >50 nmol/L, whereas this effect is minimally evident in the presence of neonatal TAQI polymorphism with neonatal 25(OH)D values <25 nmol/L. The implication of these findings could be incorporated in daily clinical practice by targeting a maternal 25(OH)D cut-off >50 nmol/L, which could be protective against any effect of genetic VDR variance polymorphism on birth anthropometry.

Low Levels of LRRK2 Gene Expression are Associated with LRRK2 SNPs and Contribute to Parkinson's Disease Progression

Parkinson's disease (PD) is a chronic neurodegenerative disease that has relatively slow progression with motor symptoms. Leucine-rich repeat kinase 2 (LRRK2) gene mutations and polymorphisms are suggested to be associated with PD. In this study, we aimed to investigate the association between single-nucleotide polymorphisms (SNPs) of the LRRK2 gene, namely, rs11176013, rs10878371, rs11835105, and PD. Genotypes of 132 PD cases and 133 healthy individuals were determined by qRT-PCR. Haplotype analysis was performed. Additionally, LRRK2 mRNA expression levels were determined in 83 PD cases and 55 healthy subjects. The relationship between LRRK2 mRNA levels, the target SNPs, and clinical data was also investigated. Our results indicated that the "GG" genotype and "G" allele of rs11176013 and the "CC" genotype and "C" allele of rs10878371 were more frequent in cases. The "GCG" haplotype was significantly more frequent in cases. LRRK2 mRNA expression levels in patients were significantly lower than those in healthy individuals. The patients with the "CC" genotype for rs10878371 and the "GG" genotype for rs11176013 had decreased LRRK2 mRNA levels. We found that the rs11176013 "GG" genotype and the rs10878371 "CC" genotype were less frequently seen in cases with akinetic rigid or combined akinetic rigid and tremor-dominant initial symptoms. Consequently, our results demonstrate that the rs11176013 and rs10878371 polymorphisms are associated with PD in a Turkish cohort, and moreover, these results suggest that these polymorphisms may affect the expression of the LRRK2 gene and disease progression and thus play a role in the pathogenesis of PD.

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.

Vitamin D receptor Fokl polymorphism is a determinant of both maternal and neonatal vitamin D concentrations at birth

Maternal vitamin D deficiency is considered to be the key determinant of the development of neonatal vitamin D deficiency at birth and during early infancy. Specific vitamin D receptor (VDR) gene polymorphisms have been associated with adverse pregnancy and offspring outcomes. The aim of this study was to evaluate the effect of maternal and neonatal VDR polymorphisms (ApaI, TaqI, BsmI, FokI, Tru9I) on maternal and neonatal vitamin D status. VDR polymorphisms were genotyped in 70 mother-neonate pairs of Greek origin, and classified according to international thresholds for Vitamin D status. Mean neonatal and maternal 25-hydroxy-vitamin D [25(OH)D] concentrations were 35 ± 20 and 47 ± 26 nmol/l, respectively. Neonatal VDR polymorphisms were not associated with neonatal 25(OH)D concentrations. In contrast, mothers with the Fokl FF polymorphism had a 70 % lower risk of vitamin D deficiency [25(OH)D <30 nmol/l] compared with ff ones, after adjustment for several confounders. They were also in 73 % and 88 % lower risk of giving birth to vitamin D deficient [25(OH)D <30 nmol/l] neonates compared with Ff and ff mothers, respectively. These results suggest a protective role of maternal Fokl FF genotype against both maternal and neonatal vitamin D deficiency. Further studies are needed to clarify the complex gene-gene and gene-environment interactions that determine vitamin D status at birth.

Association between vitamin D receptor polymorphisms and susceptibility to Parkinson's disease: An updated meta-analysis

The relationships between vitamin D receptor (VDR) gene polymorphisms, particularly ApaI, BsmI, FokI, and TaqI, and Parkinson's disease (PD) has received increasing attention in the research community. However, as the results yielded by this increased research have hitherto conflicted, we performed an updated meta-analysis of reports on the relationships between VDR polymorphisms and PD published before October 2019 that we collected from the PUBMED, EMBASE, EBSCO, China National Knowledge Infrastructure (CNKI), and Wanfang databases. The ten articles that met our screening criteria included 2782 patients and 3194 healthy controls. All the data that we received were analyzed with Stata 12.0 statistical software. The odds ratio (OR) and 95 % confidence intervals (CIs) were used to determine the relationship between VDR gene diversity and PD. While we did not find a significant correlation between the ApaI, BsmI, and TaqI polymorphisms and the risk of PD in any of the considered genetic models, we found a clear association between the FokI polymorphism and susceptibility to PD (C vs. T: OR = 1.246, 95 % CI: 1.101-1.411, P = 0; CC vs. TT: OR = 1.630, 95 % CI: 1.243-2.139, P = 0; CT vs. TT: OR = 1.382, 95 % CI: 1.059-1.804, P = 0.017; CC + CT vs. TT: OR = 1.491, 95 % CI: 1.159-1.919,P = 0.002; CC vs. CT + TT: OR = 1.261, 95 % CI: 1.062-1.496, P = 0.008). Our subgroup analysis performed according to ethnicity revealed that FokI increased the risk of PD in Asian populations (C vs. T: OR = 1.261, 95 % CI: 1.080-1.472, P = 0.003; CC vs. TT: OR = 1.664, 95 % CI: 1.189-2.330, P = 0.003; CT vs.TT: OR = 1.387, 95 % CI: 1.000-1.925, P = 0.05; CC + CT vs. TT: OR = 1.497, 95 % CI: 1.098-2.042, P = 0.011; CC vs. CT + TT: OR = 1.285, 95 % CI: 1.036-1.593, P = 0.022). Overall, the gene polymorphism of FokI only increases the risk of PD among Asian populations. Given the limited sample size of this study, the findings should be carefully explained.

Genetic, environmental and biomarker considerations delineating the regulatory effects of vitamin D on central nervous system function

Studies show that vitamin D (vit-D) (25(OH)D), the bioactive metabolite (1,25(OH)2D3) and vit-D receptors (vit-D receptor; protein disulphide isomerase, family A member 3) are expressed throughout the brain, particularly in regions pivotal to learning and memory. This has led to the paradigm that avoiding vit-D deficiency is important to preserve cognitive function. However, presently, it is not clear if the common clinical measure of serum 25(OH)D serves as a robust surrogate marker for central nervous system (CNS) homeostasis or function. Indeed, recent studies report CNS biosynthesis of endogenous 25(OH)D, the CNS expression of the CYP group of enzymes which catalyse conversion to 1,25(OH)2D3 and thereafter, deactivation. Moreover, in the periphery, there is significant ethnic/genetic heterogeneity in vit-D conversion to 1,25(OH)2D3 and there is a paucity of studies which have actually investigated vit-D kinetics across the cerebrovasculature. Compared with peripheral organs, the CNS also has differential expression of receptors that trigger cellular response to 1,25(OH)2D3 metabolites. To holistically consider the putative association of peripheral (blood) abundance of 25(OH)D on cognitive function, herein, we have reviewed population and genetic studies, pre-clinical and clinical intervention studies and moreover have considered potential confounders of vit-D analysis.

Posttraumatic stress disorder is associated with reduced vitamin D levels and functional polymorphisms of the vitamin D binding-protein in a population-based sample

OBJECTIVE

Low levels of vitamin D were found to be associated with different mental disorders. However, the role of vitamin D in the pathogenesis of PTSD is unclear. In this study, we aimed at investigating whether PTSD is linked to reduced vitamin D levels and vitamin D deficiency. Moreover, we sought to investigate the role of the vitamin D-binding protein (also group-specific component or Gc) by testing if two functional polymorphisms (rs4588 and rs7041) were associated with vitamin D levels and PTSD.

METHODS

Serum levels of total 25(OH)D were measured in a general-population sample of the Study of Health in Pomerania (SHIP-1). The number of traumatic events and status of PTSD were assessed using the PTSD module of the Structured Clinical Interview for the DSM-IV. Study participants were genotyped for rs4588 and rs7041. Associations of 25(OH)D levels and the genotypes with PTSD were tested in subjects with at least one traumatic event (n = 1653).

RESULTS

25(OH)D levels were inversely (OR: 0.96; p = 0.044) and vitamin D deficiency was positively (OR = 2.02; p = 0.028) associated with PTSD. Both polymorphisms of the Gc were associated with 25(OH)D levels and PTSD: Carriers of the CC-genotype of rs4588 showed significantly higher 25(OH)D levels (ß = 0.179, p < 0.001) and lower odds for PTSD (OR = 0.35; p = 0.023) compared to the AA-genotype. Likewise, carriers of the TT-allele of rs7041 showed lower 25(OH)D levels (-0.122; p < 0.001) and increased odds for PTSD (OR = 2.80; p = 0.015) compared to the GG-genotype.

CONCLUSIONS

Our results suggest that an altered vitamin D metabolism may be involved in the pathophysiology of PTSD. Also, genotypes of the Gc and thus Gc serum levels may impact on PTSD development over and above the effects of 25(OH)D. Our findings contribute to explain the associations of PTSD with different mental and physical disorders.

Molecular basis of vitamin D action in neurodegeneration: the story of a team perspective

Vitamin D, a secosteroid hormone, has, over the years, mainly been known for its classic role in the maintenance of calcium homeostasis of the human body. However, there is increasing understanding that vitamin D contributes to the regulation of Ca²⁺ homeostasis, especially via voltage-gated calcium channels, in another major organ that uses calcium, the brain. Almost 30 years ago, the role of dysregulation in the aging brain and in Alzheimer's disease (AD) gave rise to the Ca²⁺ hypothesis of brain aging and dementia. We thus made calcium homeostasis the starting point of our studies, proposing the notion that the consequences of long-term deficiency and/or inefficient utilization of vitamin D may cause the disruption of calcium homeostasis in neurons, this creating a vulnerability of neurons to aging and neurodegeneration. In this mini-review, we aim to describe the potential of vitamin D (cholecalciferol) as a neurosteroid based on our findings and conclusions.

Vitamin D basis of Alzheimer's disease: from genetics to biomarkers

Alzheimer's disease (AD) is a progressive neurodegenerative disorder seen mostly in the elderly population. While to date AD research has focused on either neurochemical disruptions, genetic studies, or the pathological hallmarks, little has been done to establish a novel approach that would encompass all three aspects, one that would overcome the current barriers in AD research and determine the cause of AD and, eventually, discover a treatment. Meanwhile, there have been strong indications in recent years that vitamin D, a secosteroid hormone, and its receptors are fundamentally involved in neurodegenerative mechanisms. Observational studies have pointed to vitamin D deficiency as a genetic risk factor for AD, Parkinson's disease (PD), vascular dementia, and multiple sclerosis (MS), as well as other neurological disorders, brought about by alterations in genes involved in metabolism, transportation, and actions of vitamin D. Molecular studies have demonstrated that vitamin D treatments prevent amyloid production while also increasing its clearance from the brain in AD. Finally, recent vitamin D intervention studies have reported significant improvement in cognitive performance in subjects with senile dementia, mild cognitive impairment, and AD. This review aims to describe how a vitamin D research strategy, fully integrating all aspects of present-day AD research, would elucidate the genetic, molecular, and biochemical background of the disease.

Amyloid Beta 1-42 Alters the Expression of miRNAs in Cortical Neurons

Recently, Aβ1-42 was demonstrated to have the potential to translocate into the nucleus and to be involved in the transcriptional regulation of certain neurodegeneration-related genes. This data raises the question of whether Aβ-induced neurodegeneration might include the expression of miRNAs. Thus, our aim in this study was to investigate the effects of Aβ1-42 on certain miRNAs which are related with vitamin D metabolism, neuronal differentiation, development, and memory. This question was investigated in primary cortical neurons that were treated with 10 μM Aβ and/or 10^-8 M 1,25-dihydroxyvitamin D3 at different time points by expression analysis of let-7a-5p, miR-26b-5p, miR-27b-3p, miR-31a-5p, miR-125b-5p, and miR-192-5p with qRT-PCR. Our data indicate that amyloid pathology has effects on the expression of miRNAs. Furthermore, some of these miRNAs simultaneously regulate the proteins or the enzymes involved in neuronal metabolism. The experimental setup that we used and the data we acquired supply valuable information about the miRNAs that play a part in the Aβ pathology and suggested Aβ as a counterpart of vitamin D at the crossroads of neuronal differentiation, development, and memory.

The Association Between Vitamin D Binding Protein Polymorphisms and Vitamin D Level on Epilepsy in China

Accumulating studies suggest the potential association between epilepsy and vitamin D (VD) in recent years. Vitamin D binding protein (VDBP) is the main VD carrier and can affect the availability of VD and its metabolites. Thus, this study aimed to investigate the association between VDBP polymorphisms and VD level on epilepsy. A total of 220 epilepsy patients and 210 health controls were enrolled and polymorphisms of VDBP (rs4588, rs7041, rs2298849, and rs2282679) genotype were detected using the PCR-ligase detection reaction method. The circulating status of VD metabolites, 25(OH)D and 24,25(OH)₂D, was detected by a validated high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method, and the VD metabolite ratio (VMR), 24,25(OH)₂D:25(OH)D, was then calculated. The frequency of rs4588(C>A) and rs2282679(A>C) genotype with AC was significantly lower among the patients relative to the controls [odds ratio, OR = 0.597, 95% confidence interval, CI = 0.401-0.890, p = 0.011 for rs4588(C>A); OR = 0.611, 95% CI = 0.409-0.912, p = 0.016 for rs2282679(A>C), respectively]. For rs7041 genotype distribution, VMR level was significantly higher in patients with GG genotype than in those carrying TT and TG genotype (p = 0.008). Our study demonstrated that the polymorphisms of VDBP rs4588 and rs2282679 may play a potentially important role in epilepsy susceptibility in Chinese Han population.

Polymorphisms in Vitamin D Receptor Genes in Association with Childhood Autism Spectrum Disorder

Both genetic and environmental factors have been implicated in the etiology of autism spectrum disorder (ASD). This case-control study aimed to determine the association of single-nucleotide polymorphisms (SNPs) rs731276 (TaqI), rs1568820 (Cdx2), rs1544410 (BsmI), and rs2228570 (FokI) in the vitamin D receptor (VDR) gene with susceptibility of childhood ASD and severity of the disease. A total of 201 children with ASD and 200 healthy controls from the Han Chinese population were recruited. SNP genotyping was carried out by TaqMan probe-based real-time PCR using genomic DNA extracted from blood cells. Among four examined SNPs, only the CT genotype (odds ratio (OR) = 1.96, 95% confidence interval (CI) = 1.05-3.68, P = 0.0351) and the C allele (OR = 1.88, 95% CI = 1.02-3.46, P = 0.0416) of the rs731276 were significantly associated with increased risks of childhood ASD. None of the SNPs were associated with severity of childhood ASD. Our results reveal that certain polymorphisms in the VDR gene are a risk factor related to childhood ASD in the Han Chinese population.

Vitamin D receptor is present on the neuronal plasma membrane and is co-localized with amyloid precursor protein, ADAM10 or Nicastrin

Our recent study indicated that vitamin D and its receptors are important parts of the amyloid processing pathway in neurons. Yet the role of vitamin D receptor (VDR) in amyloid pathogenesis is complex and all regulations over the production of amyloid beta cannot be explained solely with the transcriptional regulatory properties of VDR. Given that we hypothesized that VDR might exist on the neuronal plasma membrane in close proximity with amyloid precursor protein (APP) and secretase complexes. The present study primarily focused on the localization of VDR in neurons and its interaction with amyloid pathology-related proteins. The localization of VDR on neuronal membranes and its co-localization with target proteins were investigated with cell surface staining followed by immunofluorescence labelling. The FpClass was used for protein-protein interaction prediction. Our results demonstrated the localization of VDR on the neuronal plasma membrane and the co-localization of VDR and APP or ADAM10 or Nicastrin and limited co-localization of VDR and PS1. E-cadherin interaction with APP or the γ-secretase complex may involve NOTCH1, NUMB, or FHL2, according to FpClass. This suggested complex might also include VDR, which greatly contributes to Ca⁺² hemostasis with its ligand vitamin D. Consequently, we suggested that VDR might be a member of this complex also with its own non-genomic action and that it can regulate the APP processing pathway in this way in neurons.

Vitamin D Receptor Regulates Amyloid Beta 1-42 Production with Protein Disulfide Isomerase A3

The challenge of understanding the biology of neuronal amyloid processing could provide a basis for understanding the amyloid pathology in Alzheimer's disease (AD). Based on our previous studies, we have suggested that AD might be the consequence of a hormonal imbalance in which the critical hormone is vitamin D. The present study primarily focused on the creation of a condition that prevents the genomic or nongenomic action of vitamin D by disrupting vitamin D receptors (VDR or PDIA3/1,25MARRS); the effects of these disruptions on the series of proteins involved in secretases that play a crucial role in amyloid pathology and on amyloid beta (Aβ) production in primary cortical neurons were observed. VDR and PDIA3/1,25MARRS genes were silenced separately or simultaneously in E16 primary rat cortical neurons. The expression of target genes involved in APP processing, including Presenilin1, Presenilin2, Nicastrin, BACE1, ADAM10, and APP, was investigated with qRT-PCR and Western blot in this model. 1,25-Dihydroxyvitamin D₃ treatments were used to verify any transcriptional regulation data gathered from siRNA treatments by determining the mRNA expression of the target genes. Immunofluorescence labeling was used for the verification of silencing experiments and intracellular Aβ1-42 production. Extracellular Aβ1-42 level was assessed with ELISA. mRNA and protein expression results showed that 1,25-dihydroxyvitamin D₃ might affect the transcriptional regulation of the genes involved in APP processing. The intracellular and extracellular Aβ1-42 measurements in our study support this suggestion. Consequently, we suggest that 1,25-dihydroxyvitamin D₃ and its receptors are important parts of the amyloid processing pathway in neurons.

Independent assortment of GC gene polymorphism (rs2282679) and 25-hydroxyvitamin D levels in coronary artery disease

Coronary artery disease (CAD) remains a major public health burden. Emerging research has suggested an association between vitamin D insufficiency and CAD. Vitamin D binding protein (VDBP) is the primary vitamin D carrier and many of its genetic polymorphisms are able to induce the expression of proteins with different affinities for the vitamin, which in turn might affect its serum levels and CAD incidence. One hundred and twelve male patients, aged between 35 and 50 years, with verified CAD and 109 age- and sex-matched controls were recruited. Genotyping was performed by the TaqMan allelic discrimination assay and plasma 25(OH)D levels were assessed by HPLC-UV. Serum parathyroid hormone (s-PTH) and VDBP levels were measured using ELISA. s-25(OH)D levels in CAD patients were significantly lower than in the controls, whereas s-PTH levels were significantly higher in the CAD patients than in the controls. There was no significant difference in the distribution of GC genotypes among both groups. s-25(OH)D showed a weak inverse correlation with s-PTH levels. Serum levels of vitamin D and PTH are highly correlated with CAD incidence. However, the s-VDBP level is associated neither with disease outcome nor with vitamin D status. The GC gene variant has no effect on 25(OH)D levels.

GC Gene Polymorphisms and Vitamin D-Binding Protein Levels Are Related to the Risk of Generalized Aggressive Periodontitis

Objective. To explore whether GC (group-specific component) rs17467825, rs4588, and rs7041 polymorphisms are associated with generalized aggressive periodontitis. Methods. This case-control study recruited 372 patients with generalized aggressive periodontitis (group AgP) and 133 periodontal healthy subjects (group HP). GC rs17467825, rs4588, and rs7041 genotypes and plasmatic vitamin D-binding protein (DBP) were measured. Analysis of single SNP and multiple SNPs was performed and relevance between plasmatic DBP and haplotypes was analyzed. Results. GC rs17467825 GG genotype was statistically associated with lower risk for generalized aggressive periodontitis under the recessive model (OR = 0.52, 95% CI: 0.30-0.92, p = 0.028). GC rs17467825 and rs4588 had strong linkage disequilibrium with r² ≥ 0.8 and D' ≥ 0.8. Haplotype (GC rs17467825, rs4588) GC was associated with the less risk for generalized aggressive periodontitis (OR = 0.29, 95% CI: 0.09-0.96, p = 0.043). In group AgP, individuals with combined genotype (GC rs17467825, rs4588) AG+CA had significantly lower plasmatic DBP level than those with the other two combined genotypes (AG+CA versus AA+CC p = 0.007; AG+CA versus GG+AA p = 0.026). Conclusions. GC rs17467825 genotype GG and haplotype (GC rs17467825, rs4588) GC are associated with generalized aggressive periodontitis. The association may be acquired through regulating DBP levels. The functions of GC gene and DBP in inflammatory disease need to be further studied.