The effect of FokI vitamin D receptor polymorphism on bone mineral density in Jordanian perimenopausal women

Association of VDR gene variant rs2228570-FokI with gestational diabetes mellitus susceptibility in Arab women

Gestational diabetes mellitus (GDM) has been linked with adverse pregnancy outcomes. Vitamin D receptor (VDR) gene variants have been associated with diabetes mellitus susceptibility and related complications. This study assessed the association between VDR gene polymorphism (rs2228570) and GDM risk among pregnant Arab women. A total of 368 pregnant Saudi women who were screened for GDM at 24-28 weeks of gestation and genotyped for the VDR gene variant (rs2228570) were included in this cross-sectional study. Circulatory insulin levels, fasting blood glucose (FBG), glycated hemoglobin (HbA1c), and vitamin D (25(OH)D) were measured. There were 108 women with GDM and 260 women without GDM. The genotype frequency of women with GDM was CC 60.2 %, CT 33.3 %, TT 6.9 %, and CT + TT 39.8 %; for non-GDM women, were CC 61.1 %, CT 31.5 %, TT 6.9 %, and CT + TT 38.4 %. No association was found between the VDR gene variant (rs2228570-FokI) and GDM susceptibility after adjustment for covariates. Serum 25(OH)D had a significant inverse association with FBG (r = -0.49, p = 0.01) and HbA1c (r = -0.45, p = 0.03) among carriers of the TT-genotype. Furthermore, a significant inverse correlation was observed between serum 25(OH)D and HOMA-β (r = -0.20, p = 0.035) in individuals with the T-allele. Among pregnant Saudi women, glycemic indices appear to be influenced by vitamin D, suggesting a possible role it may play in mitigating the metabolic changes associated with GDM, particularly among individuals with specific genetic backgrounds. In our study population, rs2228570-FokI did not appear to be a significant contributor to GDM risk.

Vitamin-related phenotypic adaptation to exposomal factors: The folate-vitamin D-exposome triad

The biological role of two key vitamins, folic acid and vitamin D is so fundamental to life processes, it follows that their UV sensitivity, dietary abundance (both key exposomal factors) and variability in dependent genes will modify their functional efficacy, particularly in the context of maintaining the integrity and function of genome and epigenome. This article therefore examines folate and vitamin D-related phenotypic adaptation to environmental factors which vary across the human life cycle as well as over an evolutionary time-scale. Molecular mechanisms, key nutrigenomic factors, phenotypic maladaptation and evolutionary models are discussed.

Maternal-fetal vitamin D receptor polymorphisms significantly associated with preterm birth

PURPOSE

Preterm birth (PTB) is a complex trait with strong genetic background, whose etiology is not fully understood. It was recently suggested that pregnancy duration is affected by fetal genetic variation even more than by the maternal genome. Vitamin D receptor (VDR) is involved in embryonic implantation and fertility. We studied the association between both maternal and neonatal vitamin D receptor (VDR) genetic variation and PTB.

METHODS

Maternal and fetal (umbilical cord) DNA was isolated from Jewish Israeli idiopathic preterm newborns (24-36 weeks, n = 146) and control term newborns (>37 weeks, n = 229). Maternal and fetal VDR polymorphisms (FokI, ApaI, BsmI, TaqI) were analyzed by restriction fragment length polymorphism analysis. Using SPSS analysis to correlate VDR genotypes with phenotypic variation: pregnancy duration, preterm birth and spontaneous miscarriages, adjusted for gravidity, parity and gender of newborn.

RESULTS

Women homozygous to VDR ApaI (AA) genotype had significant twofold increase risk for PTB [OR 1.973, (CI) 1.183-3.289, p = 0.009] compared to heterozygous women. Male newborns had significant (p < 0.05) 1.73-fold increase of PTB. Women with history of previous (≥1) spontaneous miscarriage had a significant increased risk for PTB if their newborn carried either of the VDR BsmI homozygous (BB or bb) genotypes compared to the heterozygous (Bb) genotype [OR 6.857, (CI) 1.273-36.934, p = 0.018 and OR 9.231, (CI) 1.753-48.618, p = 0.008, respectively], or VDR ApaI homozygous (AA or aa) genotype compared to heterozygous (Aa) genotype [OR 4.33, (CI) 1.029-18.257, p = 0.046 and OR 7.2, (CI) 1.34-38.917, p = 0.021, respectively].

CONCLUSIONS

We show association between maternal and fetal VDR genotype variants with PTB.

Relationship between vitamin D receptor gene polymorphisms, cardiovascular risk factors and adiponectin in a healthy young population

AIM

To explore the association between VDR polymorphisms and several cardiovascular risk factors and adiponectin.

MATERIALS & METHODS

Three-hundred and sixty-nine healthy students were randomly selected. Five VDR polymorphisms were genotyped: BsmI rs1544410; Cdx2 rs11568820; ApaI rs7975232; TaqI rs731236 and FokI rs2228570. BMI, waist circumference (WC), blood pressure, lipid/glycemic profiles and adiponectin were assessed.

RESULTS

In men, BsmI, ApaI and TaqI were associated with BMI and WC (p < 0.05). FokI was associated with triglycerides and high-density lipoprotein levels (p = 0.0036; p = 0.005) whereas BsmI and Cdx2 were associated with adiponectin levels (p = 0.026; p = 0.048). Associations disappeared after BMI and WC adjustments. In women, ApaI was associated with systolic blood pressure (p = 0.02).

CONCLUSION

Our study demonstrated a gender-specific difference between VDR SNPs and various cardiovascular risk factors and adiponectin.

Cdx-2 polymorphism in Vitamin D Receptor gene was associated with serum 25-hydroxyvitamin D levels, bone mineral density and fracture in middle-aged and elderly Chinese women

The aim of the current study was to examine the relationship between Cdx-2 polymorphism in the promoter region of the VDR gene and serum 25-hydroxyvitamin D (25(OH)D) levels, bone mineral density (BMD) and fracture in Chinese population. This was a cross-sectional study, which included 738 individuals (428 women and 310 men) aged 45 years or older. In women, the association of Cdx-2 polymorphism with serum 25(OH)D levels was significant adjusting for age, BMI, estimated glomerular filtration rate, menopausal status and season of blood collection (P = 0.002). Cdx-2 polymorphism was associated with lumbar spine BMD adjusted for age, BMI, menopausal status and serum 25(OH)D in women (P = 0.005). But it was not associated with femoral neck BMD or total hip BMD in women. In women, Cdx-2 polymorphism was also associated with fracture adjusted for age, BMI, menopausal status, serum 25(OH)D and total hip BMD (P = 0.03). Carriers of AA and AG genotypes was associated with a higher odds of fracture compared with the carriers of GG genotype (OR = 2.14, 95% CI 1.04-4.42 and OR = 1.90, 95% CI 1.03-3.51). In men, Cdx-2 polymorphism was not associated with serum 25(OH)D levels, BMD or fracture. Our results indicate that the association of Cdx-2 polymorphism in the VDR gene with serum 25(OH)D levels, BMD and fracture may have sex differences. Cdx-2 polymorphism in the VDR gene may affect the serum 25(OH)D concentrations and the risk of osteoporosis and fracture in middle-aged and elderly Chinese women.

A 2-year prospective densitometric study on the influence of Fok-I gene polymorphism in young patients with thalassaemia major

This study is to estimate the degree of genetic contribution of Fok-I gene polymorphism of Vitamin D receptor to bone mass in patients with thalassaemia. Results indicate a protective role of the f allele of the Fok-I gene polymorphism when found in homozygosity on bone mineral density of young thalassemic patients.

INTRODUCTION

The purpose of this study is to estimate prospectively the degree of genetic contribution of Fok-I gene polymorphism of vitamin D receptor (VDR) to the evolution of bone mass in patients with beta-thalassemia major (b-TH).

METHODS

Sixty-four children and young adults (33 males and 31 females) with mean decimal age of 23.20 ± 5.41 (range 9.25-32.41 years) were recruited in this study. All patients were genotyping for Fok-I gene polymorphism and were assessed with dual energy X-ray absorptiometry (DXA) at baseline and 2 years after. Z-scores were calculated based on normal age and sex matched Caucasian population. Metabolites of vitamin D, intact PTH, total calcium, inorganic phosphorous, and alkaline phosphatase were measured at the serum pre-transfusion.

RESULTS

A moderate proportion of patients had decreased DXA Z-scores (Z-score ≤-2) predominately in total hip (31 %) and secondary in lumbar spine (15.6 %). Patients being homozygous for the f allele had apparently higher BMD Z-scores compared with those carrying the F allele in homo- or heterozygosity, however, with a difference that did not reached significance. Interestingly enough, a significant deterioration in BMD Z-scores measured at femur (FF: P = 0.004 Ff: P < 0.001, ff: P = 0.024) and total hip (FF: P = 0.022, Ff: P = 0.005) was recorded for all type of genotypes, except for ff genotype and with regard to the total hip DXA values. An increased prevalence of serum 25(OH)D3 deficiency (59.4 %) and 25(OH)D3 borderline (12.5 %) was recorded.

CONCLUSION

Our study indicates a protective role of the f allele of the Fok-I gene polymorphism when found in homozygosity on bone mineral density of young patients with b-TM.

The influence of vitamin D receptor genetic variants on bone mineral density and osteoporosis in Chinese postmenopausal women

Growing evidence indicates that the vitamin D receptor (VDR) gene is an important candidate gene for influencing the development of osteoporosis. The aim of the study was to evaluate the potential association between genetic variants of VDR gene and bone mineral density (BMD) and osteoporosis in Chinese postmenopausal women. The study included 970 Chinese postmenopausal women at the postmenopausal osteoporosis (482) and healthy controls (488). The BMD of lumbar spine (L_2–4 anterior-posterior view), femoral neck hip, and total hip was evaluated using the Norland XR-46 dual energy X-ray absorptiometry (DEXA). The genotypes of VDR genetic variants were determined by the created restriction site-PCR (CRS-PCR) and confirmed by DNA sequencing methods. Our data indicated that the VDR p.Glicine (Gly)14 alanine (Ala) and p.histidine (His) 305 glutanine (Gln) genetic variants were statistically associated with adjusted femoral neck hip BMD, adjusted lumbar spine BMD, and adjusted total hip BMD (P values < 0.05). Results from this study suggest that the VDR p.Gly14Ala and p.His305Gln genetic variants are significantly associated with BMD decrease in Chinese postmenopausal women and might be used as molecular markers for assessing the risk of BMD and osteoporosis.

Association between vitamin D receptor gene polymorphisms (Fok1 and Bsm1) and osteoporosis: a systematic review

Osteoporosis is a health concern characterized by reduced bone mineral density (BMD) and increased risk of fragility fractures. Many studies have investigated the association between genetic variants and osteoporosis. Polymorphism and allelic variations in the vitamin D receptor gene (VDR) have been found to be associated with bone mineral density. However, many studies have not been able to find this association. Literature review was conducted in several databases, including MEDLINE/Pubmed, Scopus, EMBASE, Ebsco, Science Citation Index Expanded, Ovid, Google Scholar, Iran Medex, Magiran and Scientific Information Database (SID) for papers published between 2000 and 2013 describing the association between Fok1 and Bsm1 polymorphisms of the VDR gene and osteoporosis risk. The majority of the revealed papers were conducted on postmenopausal women. Also, more than 50% studies reported significant relation between Fok1, Bsm1 and osteoporosis. Larger and more rigorous analytical studies with consideration of gene-gene and gene-environment interactions are needed to further dissect the mechanisms by which VDR polymorphisms influence osteoporosis.