Endocrinopathies in Hemoglobinopathies: What Is the Role of Iron?

Hemoglobinopathies, including β-thalassemia and sickle cell disease (SCD), are common genetic blood disorders. Endocrine disorders are frequent manifestations of organ damage observed mainly in patients with β-thalassemia and rarely in SCD. Iron overload, oxidative stress-induced cellular damage, chronic anemia, and HCV infection contribute to the development of endocrinopathies in β-thalassemia. The above factors, combined with vaso-occlusive events and microcirculation defects, are crucial for endocrine dysfunction in SCD patients. These endocrinopathies include diabetes mellitus, hypothyroidism, parathyroid dysfunction, gonadal and growth failure, osteoporosis, and adrenal insufficiency, affecting the quality of life of these patients. Thus, we aim to provide current knowledge and data about the epidemiology, pathogenesis, diagnosis, and management of endocrine disorders in β-thalassemia and SCD. We conducted a comprehensive review of the literature and examined the available data, mostly using the PubMed and Medline search engines for original articles. In the era of precision medicine, more studies investigating the potential role of genetic modifiers in the development of endocrinopathies in hemoglobinopathies are essential.

TNF-alpha gene polymorphism and its relation to vitamin D, calcium, alkaline phosphatase and ferritin status in Iraqi beta thalassemia patients

Introduction and Aim: Due to a lack of effective medications, beta-thalassemia is a serious issue in Iraq. Thus, the current investigation aimed to explore the relationship between TNF-alpha gene polymorphism G/A (rs 1800629), Vitamin D (Vit D), Calcium (Ca), alkaline phosphatase (ALP), and ferritin status in Iraqi beta thalassemia major and intermediate patients.   Materials and Methods: Blood samples were collected from 46 patients suffering from thalassemia major (TM) plus 48 patients suffering from thalassemia intermediate (TI) and 48 of apparently healthy volunteers as control group aged 18-60 years, from Ibn Al-Baladi Hospital, Baghdad.   Results: Studies for the distribution of TNF- alpha G/A (rs 1800629) genotype showed that among TM patients and TI patients, the prevalence of the mutant AA genotype (rs 1800629) was higher in TM patients, while in the control group, it was lower.  Similarly, for the wild genotype (GG), the prevalence was highest in control group followed by T1 and TM patients. The frequency of A allele was high in TM patients, while the G allele frequency was more in the control group. Results also showed that the TNF- alpha genotype variations influenced Vitamin D, Calcium, ALP, and ferritin levels in TM and TI patients, wherein the patients with TNF-alpha mutant genotype (AA) were associated with highest levels of ferritin and ALP among all genotypes groups, while the patients of with TNF-alpha wild genotype (GG) were associated with high levels of Vitamin D and Calcium among all genotypes groups.   Conclusion: Patients with at least one copy of (A) allele had a higher risk of TM and TI and there was an association between the heterogeneous (GA) and mutant (AA) genotypes, also presence of (A) allele with status differences of Vit D, Ca, ALP, and ferritin in Iraqi beta thalassemia major and intermediate patients.

Bone Mineral Density, Serum Calcium, and Vitamin D Levels in Adult Thalassemia Major Patients: Experience From a Single Center in Eastern India

Background and objective Patients suffering from thalassemia major are at higher risk of osteoporosis. Due to their decreased life expectancy, the number of adult patients is low. However, their bone health is rarely checked in developing countries like India. There is no data available in the literature on the bone mineral density (BMD) of adult (aged ≥18 years) thalassemia major patients in eastern India. In this study, we aimed to measure the BMD and serum calcium and vitamin D levels in adult thalassemia major patients and to compare them with healthy controls. Materials and methods We conducted this cross-sectional observational study at a tertiary care hospital in eastern India. We recruited adult thalassemia major patients who were not on calcium or vitamin D supplements. Their BMD was measured by dual-energy X-ray absorptiometry (DXA) on the lumbar spine (L1-L4). Venous blood was tested for serum calcium and vitamin D levels. We compared the parameters between the cases and controls by using the Mann-Whitney U test. Results A total of 31 (male = 19, female = 12) patients with a median age of 28 years comprised the case group. Age- and sex-matched controls showed similar height but higher weight and BMI. The serum calcium level was similar (p = 0.43) in the case and control groups but T-score (p = 0.0003) and vitamin D levels (p: <0.0001) were significantly lower in thalassemia major patients. Conclusion Based on our findings, adult thalassemia major patients have lower BMD and vitamin D levels. Although the serum calcium may be normal in these patients, they should still be screened both for BMD and vitamin D for prompt and early detection of risks and complications so that a proper management strategy can be implemented.

Nutrition in Thalassemia: A Systematic Review of Deficiency, Relations to Morbidity, and Supplementation Recommendations

BACKGROUND

Reports of nutritional deficiencies in patients with thalassemia (Thal) are common. Despite its importance, however, nutritionally focused research in Thal has been limited by inadequate sample size, inconsistent methodology, a lack of control comparisons, and few interventional trials. Due to these limitations, clinicians lack evidence-based nutrition recommendations to support clinical decision-making. This systematic review summarizes observed relationships between nutrition and morbidity in Thal published in the last 3 decades.

METHODS

PubMed, Web of Science, and Embase were screened for articles pertaining to nutrition in Thal using comprehensive search terms. Studies performed in humans, written in English, and published between 1990 and 2020 were included. Over 2100 manuscripts were identified, from which 97 were included.

RESULTS

Patients with Thal were most often deficient in vitamins A, C, D, selenium, and zinc. Prevalence of nutritional deficiency was positively correlated with age and iron overload. Evidence to support the role of vitamin D and zinc for bone health was observed; zinc was also found to improve glucose metabolism.

CONCLUSIONS

Due to the risk for multinutrient deficiency, nutritional status should be assessed annually in patients with Thal with prompt nutrient replacement when deficiency is detected. Routine supplementation with vitamin D and zinc is recommended.

Vitamin D level, lipid profile, and vitamin D receptor and transporter gene variants in sickle cell disease patients from Kurdistan of Iraq

Introduction

Sickle cell disease (SCD) patients are susceptible to the development of vitamin D deficiency (VDD). Vitamin D through binding to vitamin D receptor (VDR) exerts its function and affects gene transcription in target tissues. VDR gene variants affect bone mineral density.

Methods

In a case‐control study, 101 SCD patients including 61 sickle cell anemia (SCA), 39 S/β‐thalassemia, and 1 HbS/HbD (SD) along with 110 healthy individuals from Kurdistan of Iraq were studied. The lipid profile, vitamin D level, FokI, and TaqI variants of VDR and group‐specific component (GC) were detected using the standard enzymatic method, the immunodiagnostic systems limited EIA kit and PCR‐RFLP methods, respectively.

Results

Around 93% and 82% of SCA and S/β‐thalassemia patients, respectively, had VDD compared to 83% of healthy individuals. Severe VDD (<10 ng/ml) was detected in 78.7% of patients with HbSS. Plasma levels of total cholesterol, HDL‐C, and LDL‐C in SCD patients were significantly lower compared to controls. Vitamin D levels were negatively correlated to TG and positively correlated to total cholesterol and HDL‐C. The frequencies of the C allele of FokI were 81.7% (p = 0.003), 80.3% (p = 0.034), and 84.6% (p = 0.011) in all SCD, SCA, and S/β‐thalassemia patients, respectively, compared to 69.1% in controls. However, no significant difference was detected comparing the frequencies of VDR TaqI and GC polymorphisms between SCD patients and controls.

Conclusion

In the present study, we found hypocholesterolemia, high prevalence of VDR FokI C allele, and low vitamin D levels among children and adults with SCD from Kurdistan of Iraq.

Vitamin D and bone health status in beta thalassemia patients-systematic review

Thalassemia is a chronic congenital disease characterized by a combination of endocrine and metabolic disorders. Bone disease is a very common complication related to the poor absorption of calcium, the secondary chronic renal disease with low vitamin D, as well as multiple endocrine risk factors. The aim of this systematic review was to estimate the prevalence of vitamin D deficiency in thalassemia, as well as its association with osteoporosis/low bone mass. A systematic review was carried out using PubMed/Medline, Cochrane, and EBSCO databases. The methodological quality of the included studies was assessed with the validated Newcastle-Ottawa Quality Assessment Scale adapted for cross-sectional studies and cohort studies respectfully and the Cochrane Collaboration for clinical trials. After application of predetermined exclusion criteria compatible with the PICOS process, a total of 12 suitable articles were identified. The prevalence of vitamin D deficiency varied considerably. Only five of the reviewed studies examined the correlation between vitamin D levels and BMD of which just three showed a statistically significant positive association of mild/moderate grade. Vitamin D deficiency is a common comorbidity in patients with thalassemia. However, both its prevalence and its severity vary considerably in different populations, and existing evidence is insufficient to conclude whether vitamin D supplementation is also associated with BMD improvement in this special population group.

Moderate to severe liver siderosis and raised AST are independent risk factors for vitamin D insufficiency in β-thalassemia patients

Numerous problematic disorders such as vitamin D (Vit-D) deficiency subsequent to large iron loading can be developed in patients with β-thalassemia. The study aimed to estimate Vit-D insufficiency and its risk factors in patients with β-thalassemia. In this multicenter and observational study, all β-thalassemia patients, who referred to 14 hospital-based thalassemia divisions or clinics in Mazandaran province, Iran were included in the study. The data belong to December 2015 until December 2019. The study population was made of transfusion dependent thalassemia (TDT) and non-transfusion-dependent thalassemia (NTDT) patients. Serum levels of 25-OHD3 have been measured by high performance liquid chromatography (HPLC) method as ng/mL. Demographic and clinical information along with some biological tests, as well as the results of T2*-weighted magnetic resonance imaging were analyzed. Of 1959 registered patients, 487 (24.9%) patients had Vit-D-related data. The prevalence of Vit-D insufficiency (< 30 ng/mL) was 41.9, 95% CI 37.5–46.3. The adjusted risks of moderate to severe liver siderosis and raised AST (aspartate aminotransferase) for Vit-D insufficiency (< 30 ng/mL) were 2.31, 95% CI 1.38–3.89 and 2.62, 95% CI 1.43–4.79, respectively. The receiver operating characteristic (ROC) curve analysis showed that the predictive accuracy of ferritin for Vit-D insufficiency status was 0.61, 95% CI 0.54–0.68 with a cutoff point of 1,078 ng/mL (P = 0.03, sensitivity 67%, specificity 49%, positive predictive value [PPV] 47% and negative predictive value [NPV] 68%). In spite of the national programs for treating Vit-D deficiency and our previous efforts for giving supplements to all patients, Vit-D insufficiency/deficiency is still common in our patients. Also, moderate to severe liver siderosis and raised AST were the independent risk factors for the Vit-D insufficiency.

Vitamin and mineral supplementation for β-thalassemia during COVID-19 pandemic

AIM

Low levels of immune-related micronutrients have been identified in β-thalassemia samples. Moreover, the excess amount of iron, contributing to oxidative stress in the pathogenesis of the disease, alters the immune system in β-thalassemia, which is important during the COVID-19 pandemic.

MATERIALS & METHODS

Searches of PUBMED and EMBASE were conducted to identify the level and supplementation of micronutrients in β-thalassemia, published from 2001-May 2020.

RESULTS

The review found six observational and five interventional studies supporting the importance of supplementing vitamins and minerals among patients with β-thalassemia.

CONCLUSION

Supplementation of immune-related vitamins and minerals might bring benefits to the immune system, especially in reducing oxidative stress in β-thalassemia.

Association of VDBP rs4701 Variant, but not VDR/RXR-α Over-Expression with Bone Mineral Density in Pediatric Well-Chelated β-Thalassemia Patients

Background

The reduced rate of bone formation despite the availability of vitamin D has been reported in β-thalassemia. Genetic factors, together with environmental ones, could be implicated in this condition. Since vitamin D binding protein (VDBP) maintains bioavailability of vitamin D which binds to vitamin D receptor (VDR)-retinoid X receptor alpha (RXRA) heterodimer to exert its molecular actions, we speculated that vitamin D metabolic-axis expression signature and variants could be potential molecular candidates for bone turnover/disease in thalassemia. To this end, this study aims to analyze VDR/RXRA expression signature, and two VDBP variants in a pilot sample of Egyptian β-thalassemia children in correlation with bone mineral density (BMD).

Patients and methods

Forty-four well-chelated β-thalassemia children and 40 unrelated controls were enrolled. The serum bone chemistry profile was measured. Peripheral blood mononuclear cells (PBMN) VDR/RXRA expression levels were quantified by Real-Time quantitative reverse transcription-polymerase chain reaction (qRT-PCR). VDBP rs7041 and rs4588 variants were identified by Real-Time allelic discrimination assay. All patients were subjected to lumbar-spine Dual-energy X-ray absorptiometry (DEXA).

Results

VDR/RXRA expressions were significantly higher in β-thalassemia children compared to controls (P = 0.001 and <0.001, respectively) and showed higher values in β-thalassemia major relative to β-thalassemia intermedia. Expression levels of both genes were not associated with sex or BMD. However, VDBP rs4701 genotyping revealed lower BMD-L4 and a higher frequency of osteoporosis.

Conclusions

β-Thalassemia children had higher expression levels of PBMN VDR/RXRA. VDBP rs4701 variant was associated with osteoporosis in our β-thalassemia patients on vitamin D supplementation. Further large-scale studies in other ethnic populations are warranted.

Bone Mineral Density and Vitamin D Receptor Genetic Variants in Egyptian Children with Beta Thalassemia Major on Vitamin D Supplementation

Background

Low bone mineral density (BMD) is a characteristic feature of Beta thalassemia major (βTM) patients. Vitamin D is important for bone mineralization. Vitamin D receptors (VDR) genetic variants may be related to vitamin D status and BMD.

Objectives

To evaluate the effect of VDR genetic variants on vitamin D levels and BMD in βTM Egyptian patients supplemented with vitamin D.

Methods

This study was conducted on forty children with βTM and seventeen unrelated healthy sex and age-matched controls. Serum calcium, phosphorus, alkaline phosphatase, ferritin, and vitamin D were measured. VDR genetic variants (BsmI, TaqI, and FokI) were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). BMD was measured by dual-energy X-ray densitometry (DEXA) of the lumbar spine.

Results

In βTM patients, 22.5% had insufficient, and 77.5% had sufficient levels of vitamin D, and no cases had vitamin D deficient. BMD Z score was significantly lower in βTM patients compared to controls (p<0.001). Osteopenia and osteoporosis of lumbar spines were observed in 70% and 22.5% of βTM patients respectively. BsmI bb and FokI Ff and ff genotypic variants were significantly associated with lower vitamin D and BMD Z score. No association was observed with TaqI genotypic variants.

Conclusions

Low BMD is prevalent in patients with βTM despite vitamin D supplementation. The BsmI bb, FokI Ff and ff genotypic variants of VDR can be considered as risk factors for the occurrence of osteoporosis in these children.

Correlation between 25-Hydroxyvitamin D and Lipid Profile among Children with Beta Thalassemia Major

BACKGROUND:

Beta thalassemia major is associated with lipid profile abnormalities, presented as a lower level of total cholesterol (TC), low-density lipoproteins (LDL), high-density lipoprotein (HDL), and higher triglyceride level; increasing risk for cardiovascular complications. The previous studies indicated that Vitamin D give a positive impact on the lipid profile in healthy children population. However, its role needs to be determined in a high-risk group of children with beta-thalassemia major.

AIM:

To determine the correlation between vitamin D (25-OHD) and lipid profile among children with beta-thalassemia major.

METHODS:

A cross-sectional study was conducted in a general tertiary hospital in Medan, Sumatera Utara, Indonesia from January to March 2018. Subjects were children aged below 18-year-old with beta-thalassemia major. The measurement of vitamin D (25-OHD) level and 10-12 hour overnight fasting serum lipid profile including total cholesterol, triglyceride, HDL, and LDL were performed. The analysis was done using Pearson’s correlation and Fisher test. P value < 0.05 was considered significant.

RESULTS:

Forty-five subjects were enrolled in this study, with serum ferritin level ranged from 1017 to 13372 ng/mL. The prevalence of vitamin D deficiency (a 25-OHD level less than 20 ng/mL) in this study was 40%, with mean value at 20.6 (SD 5.3) ng/mL. The markers for cardiovascular risk were observed to be elevated, both in Atherogenic Index Plasma (0.32 ± 0.25) and TC: HDL ratio (4.2 ± 1.5). Statistical analysis revealed that Vitamin D had positive correlation with total cholesterol (r = 0.302, p = 0.044) and HDL (r = 0.297, p = 0.048). There was no significant correlation between both vitamin D and triglyceride (p = 0.305), or vitamin D and LDL (p = 0.727).

CONCLUSION:

Vitamin D correlated positively with total cholesterol and HDL in children with beta-thalassemia major. Positive correlation to HDL indicated a beneficial effect of vitamin D to reduce the risk of cardiovascular complication.

Vitamin D deficiency and its relationship with cardiac iron and function in patients with transfusion-dependent thalassemia at Chiang Mai University Hospital

BACKGROUND

Vitamin D deficiency is common in patients with thalassemia. Vitamin D deficiency could be related to cardiac dysfunction. Increased parathyroid hormone (PTH) is also known to be associated with heart failure.

OBJECTIVES

To determine the prevalence of Vitamin D deficiency and to explore the impact of Vitamin D deficiency on cardiac iron and function in patients with transfusion-dependent thalassemia.

METHOD

A cross-sectional study in patients with Transfusion-dependent thalassemia was conducted. Patients with liver disease, renal disease, type 1 diabetes, malabsorption, hypercortisolism, malignancy, and contraindication for MRI were excluded. Calcium, phosphate, PTH, vitamin D-25OH were measured. CardiacT2^* and liver iron concentration (LIC) and left ventricular ejection fraction (LVEF) were determined. Results Sixty-one (33M/28F) patients with Transfusion-dependent thalassemia were enrolled. The prevalence of Vitamin D deficiency was 50.8%. Patients with cardiac siderosis had tendency for lower D-25OH than those without siderosis (15.9 (11.7-20.0) vs. 20.2 (15.85-22.3) ng/mL); p = 0.06). Serum calcium, phosphate, PTH, LIC, cardiac T2^*, and LVEF were not different between the groups with or without Vitamin D deficiency. Patients with Vitamin D deficiency had significantly lower hemoglobin levels compared to those without Vitamin D deficiency (7.5 (6.93-8.33) vs. 8.1 (7.30-8.50) g/dL; p = 0.04). The median hemoglobin in the last 12 months was significantly correlated with D-25OH. Cardiac T2^* had significant correlation with PTH.

CONCLUSION

Vitamin D deficiency is prevalent in patients with Transfusion-dependent thalassemia. Vitamin D level is correlated with hemoglobin level. Vitamin D status should be routinely assessed in these patients. Low PTH is correlated with increased cardiac iron. This study did not demonstrate an association between Vitamin D deficiency and cardiac iron or function in patients with Transfusion-dependent thalassemia.

Minerals in thalassaemia major patients: An overview

Thalassaemia major (TM) is a hereditary blood disease characterised by reduced or absent production of beta globin chains. Erythrocyte transfusions are given to raise the haemoglobin level in patients with thalassaemia major. However, transfusions have been related to increased risk of iron overload and tissue damage related to excess iron. Both elevated oxidative stress due to iron overload and increased hemolysis lead to over utilisation of minerals required for antioxidant enzymes activities. Iron chelators have been used to prevent iron overload in thalassaemia major patients, but these chelators have the possibility of removing minerals from the body. Thalassaemia patients are more at risk for mineral deficiency because of increased oxidative stress and iron chelation therapies. Growth and maturational delay, cardiomyopathy, endocrinopathies and osteoporosis are the complications of thalassaemia. Minerals may play a particular role to prevent these complications. In the current review, we provide an overview of minerals including zinc (Zn), copper (Cu), selenium (Se), magnesium (Mg) and calcium (Ca) in thalassaemia major patients. We, also, underline that some complications of thalassaemia can be caused by an increased need for minerals or lack of the minerals.

Risk factors for osteoporosis and the relationship between osteoporosis and hemoglobin level in adult patients with thalassemia in Rajavithi hospital

Background

Bone complications are common in patients with thalassemia.

Objectives

To assess risk factors for osteoporosis in patients with nonmajor thalassemia and its prevalence in randomly selected adult patients in Thailand.

Patients and methods

We included 190 adult patients (58 men and 132 women) with thalassemia intermedia or minor in this cross-sectional study. Patients with untreated hypogonadism, untreated hypothyroidism, menopause, and with a history of treatment with medications that have effects on skeletal or bone metabolism were excluded. Bone mass density (BMD) of the femoral neck was measured by calibrated dual-energy X-ray absorptiometry. Independent factors likely to be associated with osteoporosis were determined and included in the analysis to ascertain possible associations.

Results

Mean age was 35.48 ± 14.11 years (range 18–87 years). The mean Z score of femoral neck was − 0.86 ± 1.14 (range −3.7–2.40). Prevalence of osteoporosis was 22/190 (11.6%). Correlation between the pretransfusion hemoglobin level and BMD score was r = 0.192, P = 0.008. Univariate analysis found low BMI was a risk factor for osteoporosis (OR = 3.09, 95% CI 1.09–8.76, P = 0.039) and iron chelation therapy was a protective factor (OR = 0.24, 95% CI 0.09–0.69, P = 0.005). Multivariate analysis did not find these factors to be significant.

Conclusions

All patients with thalassemia at risk of osteoporosis should be screened periodically for bone disease. The uncertainty and disagreements as to the potential role of different factors indicate the necessity for further studies to recognize the pathophysiological basis of this serious complication of thalassemia.

Management of beta-thalassemia-associated osteoporosis

Beta-Thalassemia-associated osteoporosis is a multifactorial and complex condition. Different acquired and genetic factors are involved in its pathogenesis. These factors produce an imbalance in bone remodeling by inhibiting osteoblast activity and increasing osteoclast function, leading to bone loss and increased fracture risk. The management of patients presenting with thalassemia-associated osteoporosis should consist of the implementation of general measures and the prescription of a specific pharmacological agent, with the aim of reducing fracture risk and preventing disability and deterioration of quality of life. General measures include control of anemia, adequate chelation therapy, healthy nutrition and lifestyle, regular exercise, adequate management of comorbid conditions, hormone replacement therapy in patients with hypogonadism, and vitamin D supplementation/therapy. Among the pharmacological agents currently available for the management of osteoporosis in postmenopausal women and men, bisphosphonates have been shown to improve bone mineral density, to reduce bone turnover, and to decrease bone/back pain in patients with thalassemia-associated osteoporosis, with a good profile of safety and tolerability. On the other hand, there are limited experiences with other pharmacological agents (e.g., denosumab or teriparatide). The complexity of this condition presents diagnostic and therapeutic challenges and underscores the importance of a comprehensive and multidisciplinary approach.

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.

Vitamin D Receptor (VDR) Gene Polymorphisms (FokI, BsmI) and their Relation to Vitamin D Status in Pediatrics βeta Thalassemia Major

Vitamin D is critical for calcium, phosphate homeostasis and for mineralization of the skeleton, especially during periods of rapid growth. Vitamin D Deficiency leads to rickets (in children) and osteomalacia (in adults). Expression and activation of the vitamin D receptor (VDR) are necessary for the effects of vitamin D, in which several single nucleotide polymorphisms have been identified especially (FokI, BsmI). In this study serum 25 (OH) vitamin D3 levels were estimated by Enzyme Linked Immunosorbent Assay [ELISA], VDR (FokI, BsmI) gene polymorphisms were analyzed by polymerase chain reaction-restriction fragment length polymorphism assay [PCR-RFLP].Serum levels of calcium, phosphorus, alkaline phosphatase and ferritin were determined in 50 Pediatrics beta thalassemia major patients and 60 controls. Patients had significantly lower serum calcium (p < 0.001) lower serum vitamin D3 (p < 0.001) with elevated levels of phosphorus (p < 0.001) and alkaline phosphatase than controls (p = 0.04). Of the patients studied, 60 % had vitamin D deficiency (<20 ng/ml), 20 % had vitamin D insufficiency (21-30 ng/ml) and 20 % had sufficient vitamin D status (>30 ng/ml). Patients harboring mutant (Ff,ff) and wild (BB) genotypes were associated with lower serum calcium (p = 0.08, 0.02) respectively, lower vitamin D3 levels (p < 0.001, 0.01) respectively. They were also suffering from more bony complications although the difference was not statistically significant (p > 0.05). In conclusion, these results suggest that the VDR (FokI, BsmI) gene polymorphisms influence vitamin D status, (Ff,ff), BB genotypes had lower vitamin D levels, so they might influence risk of development of bone diseases in beta thalassemia major.

Vitamin D receptor gene polymorphisms and the risk of rickets among Asians: a meta-analysis

AIMS

To evaluate the association between vitamin D receptor (VDR) gene polymorphisms and the risk of rickets among Asians.

METHODS

Eligible studies were included in our meta-analysis by searching PubMed, Embase, Cochrane and China National Knowledge Infrastructure databases according to a predefined criteria. A random effects model was used to calculate the combined ORs and its corresponding 95% CI.

RESULTS

16 studies were recruited for the analysis of the association between VDR BsmI (rs1544410), TaqI (rs731236), FokI (rs2228570) and ApaI (rs7975232) gene polymorphisms and the risk of rickets among Asians, most of whom were from China. B allele/BB genotype was associated with the susceptibility of rickets (p=0.017 and 0.044, respectively), and bb genotype was associated with lower risk of rickets (p=0.033). F allele/FF genotype was associated with the susceptibility of rickets (p<10(-4)), and ff genotype was associated with lower risk of rickets (p<10(-4)). AA genotype was associated with the onset of rickets (p=0.044). No significant association was observed between TaqI polymorphism the risk of rickets. A allele/aa genotype was not associated with the risk of rickets. No evidence of publication bias was observed.

CONCLUSIONS

B allele/BB genotype at the BsmI site, F allele/FF genotype at the FokI site and AA genotype at the ApaI site may be risk factors for the onset of rickets among Asians; bb genotype at the BsmI site and ff genotype at the FokI site may be protective factors against the risk of rickets among Asians.

Vitamin d status in thalassemia major: an update

The survival of patients with thalassemia major has progressively improved with advances in therapy; however, osteoporosis and cardiac dysfunction remain frequent complications. Adequate circulating levels of vitamin D are essential for optimal skeletal health and reducing fracture risk. Vitamin D deficiency and insufficiency is reported to be high in thalassemic patients in many countries despite the presence of good sunshine and routine prescription of 400-1,000 IU vitamin D per day. The risk of vitamin D deficiency in thalassemia and its relation to bone disease; including osteoporosis, rickets, scoliosis, spinal deformities and fractures as well as to cardiac dysfunction is discussed in this mini-review. Monitoring and maintaining normal serum level of 25-OH vitamin D through oral intake of vitamin D and early correction of VDD by oral or parental use of vitamin D may significantly improve bone mineral accretion and ameliorate cardiac function.