维生素D受体基因多态性与维生素D缺乏性佝偻病易感性的研究

目的 通过研究维生素D受体(VDR)基因多态性与维生素D缺乏性佝偻病易感性的相关性,探讨维生素D缺乏性佝偻病的遗传易感因素。方法 利用限制性内切酶FokI,应用聚合酶链反应-限制性片段长度多态性(PCR—RFLP)分析、基因测序等技术测定48例维生素D缺乏性佝偻病患儿(病例组)和92名正常儿童(对照组)的VDR基因多态性,比较两组VDR基因型和等位基因的分布频率,并计算基因型优势比(OR)。结果 在48例佝偻病患儿中FF、Ff和ff基因型分布频率分别为46％、33％和21％;而在92名正常儿童中FF、Ff和ff基因型分布频率分别为22％、52％和26％。两组VDR基因型的分布频率差异有显著性(x^2=8．912,P=0．012),病例组中FF基因型占明显优势(OR=3．046)。两组VDR基因等位基因的分布频率差异也有显著性(x^2=5．451,P=0．020),病例组中F等位基因分布频率高于对照组。结论 VDR基因多态性与维生素D缺乏性佝偻病有相关性,提示VDR基因多态性可能在决定个体维生素D缺乏性佝偻病遗传易感性方面有重要作用。     

Vitamin D receptor gene polymorphisms in Turkish children with vitamin D deficient rickets

Vitamin D deficient rickets is prevalent in Turkey and a considerable number of children are at risk of growth retardation, impaired bone formation and fracture. In order to check whether vitamin D receptor (VDR) gene polymorphism relates to the vitamin D deficient rickets, we analyzed VDR gene FokI, TaqI and ApaI polymorphisms in 24 Turkish vitamin D deficient rickets patients and 100 healthy controls. We found that "A" (ApaI) allele is more abundant in patients than controls (83 vs 57%, p = 0.002) but there were no significant differences for FokI (p = 0.693) and TaqI (p = 0.804) allele frequencies between patients and controls. We also showed that the frequency of Tt and Aa genotypes was significantly decreased in patients. Our results indicated that VDR gene polymorphisms might be an important factor for genetic susceptibility to vitamin D deficient rickets in the Turkish population.     

维生素D缺乏性佝偻病遗传易感性的研究

目的：遗传因素是否参与维生素D缺乏性佝偻病目前尚未明了。拟通过研究维生素D受体基因多态性与维生素D缺乏性佝偻病易感性的相关性,探讨维生素D缺乏性佝偻病的遗传易感性。方法：应用聚合酶链反应-限制性片段长度多态性(PCR-RFLP)分析技术检测159例维生素D缺乏性佝偻病儿童和78例正常儿童(对照组)维生素D受体(VDR)基因FokI位点的多态性,比较两组之间VDR基因型和等位基因的频率。结果：维生素D缺乏性佝偻病患儿和对照组儿童的VDR基因FokI位点基因型分布频率分别为:FF(37%),Ff(51%),ff(12%)和FF(18%),Ff(55%),ff(27%),两组之间的差异有显著性(χ20.01(2)=9.210,χ2=13.3880,P<0.01);佝偻病患儿和对照组儿童的VDR基因FokI位点等位基因分布频率分别为:F(63%),f(37%)和F(46%),f(54%),两组之间的差异有显著性(χ2=6.18,P<0.05)。佝偻病患儿F等位基因分布频率明显高于对照组人群(63%vs46%)两组之间的差异有显著性;而佝偻病患儿f等位基因频率显著低于对照组(37%vs 54%)。结论：VDR基因FokI酶切位点的多态性可能与维生素D缺乏性佝偻病的遗传易感性有关。     

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目的 探讨维生素D受体基因多态性与维生素D缺乏性佝偻病(佝偻病)遗传易感性的关系.方法 应用聚合酶链反应-限制性片段长度多态性(PCR-RFLP)分析技术检测2003年10月至2004年10月159例佝偻病患儿和78名健康儿童(对照组)VDR基因Bsm Ⅰ位点的多态性,比较两组之间VDR基因型和基因分布.结果 佝偻病患儿和对照组儿童的VDR基因Bsm Ⅰ位点基因型分布分别为:BB(0%),Bb(15.7%),bb(84.3%)和BB(0%),Bb(11.5%),bb(88.5%),两组间差异无统计学意义(P>0.05);佝偻病患儿和对照组儿童的VDR基因BsmⅠ位点等位基因分布分别为:B(7.9%),b(92.1%)和B(5.8%),b(94.2%),两组间差异无统计学意义(P>0.05).结论 VDR基因Bsm Ⅰ酶切住点的多态性与维生素D缺乏性佝偻病的遗传易感性相关关系尚须大样本进一步确定.     

Vitamin D dependent rickets, diagnostic and therapeutic difficulties: two case reports

There are two types of vitamin D dependent rickets (VDDR) that cause rickets in children. Vitamin D dependent rickets type 1 (VDDR-I) is caused by an inborn error of vitamin D metabolism, which interferes with renal conversion of calcidiol (25OHD) to calcitriol (1,25(OH)2D) by the enzyme 1alpha-hydroxylase. Vitamin D dependent rickets type 2 (VDDR-II) is caused by a defect in the vitamin D receptor (VDR). We report cases of two African children affected by VDDR-I and VDDR-II, respectively. Establishing an early diagnosis of these genetic forms of rickets is challenging, especially in developing countries where nutritional rickets (NR) is the most common variety of the disease. A prompt diagnosis is necessary to initiate adequate treatment, resolve biochemical features and prevent complications, such as severe deformities that may require surgical intervention.     

维生素D受体多态性与晚发性佝偻病易感性研究

目的研究维生素D受体基因起始密码子（VDRSC）多态性在晚发性佝偻病组、维生素D缺乏状态组及正常对照组中分布频率的差异,探讨晚发性佝偻病的遗传易感因素。方法用聚合酶链反应——限制性长度多态性（RFLP）分析晚发性佝偻病组30例、维生素D缺乏状态组35例以及正常对照组60例VDRSC多态性的分布频率。结果三组VDRSC基因型分布频率差异有统计学意义（χ^2=13．184,P=0．010）;等位基因分布频率差异也有统计学意义（χ^2=8．975,P=0．011）。组间两两比较晚发性佝偻病组VDRSC基因型和等位基因与其他两组比较差异有统计学意义,其FF型频率（56．7％）明显高于正常对照组（21．7％,P=0．006）,也明显高于维生素D缺乏状态组（22．9％,P=0．002）;晚发性佝偻病组F型（70．0％）明显高于正常对照组（48．3％,P=0．006）,也明显高于维生素D缺乏状态组（47．1％,P=0．009）。多项分类Logistic回归分析结果显示,在调整了其他危险因素后,FF型仍是晚发性佝偻病的危险因素,相对危险度（OR）=3．120。结论VDRSC多态性可能决定晚发性佝偻病的遗传易感性。     

Yogurt. Contributory factor in development of nutritional rickets

Vitamin D deficient rickets occurred in a 15-month-old black girl for whom yogurt had been substituted for milk products. Investigation determined that commercially available yogurt contains no vitamin D, and that this fact is not generally recognized by lay persons and health professionals. Use of yogurt as a major source of nutritional intake in infants and young children may be a contributory factor in development of vitamin D deficiency rickets.     

Deficiency rickets: the current situation in France and Algeria

Persisting vitamin D deficiency rickets in France results from the climatic, environmental and geographic situation of this country. Although systematic administration of vitamin D supplements to infants greatly reduced the prevalence of rickets among infants, clinical and/or biological signs of vitamin D deficiency are still found in children and adolescents, mainly during the winter and in populations vulnerable for economic, cultural or religious reasons. Signs of vitamin D deficiency are also found, during the winter-spring seasons, in pregnant women and their newborns living in urban areas. Such vitamin D deficiencies could be overcome by vitamin D supplementation to susceptible populations. In Algeria, vitamin D deficiency rickets present a continuing public health problem. The persisting high incidence of rickets among children appears to result mainly from economic and cultural factors. Vitamin D supplementation and health education are mandatory to reduce the prevalence of vitamin D deficiency among pregnant women and the occurrence of vitamin D deficiency rickets in infants, whether breast-fed or not.     

Factors causing rickets in institutionalised handicapped children on anticonvulsant therapy.

An epidemiological study on vitamin D-dependent rickets was carried out in severely handicapped institutionalised children on long-term anticonvulsant therapy. Nine (10%) of 94 patients had overt rickets on the basis of roentgenological bone changes and biochemical indices, but 46 patients in hospital without medication, and 50 epileptic patients attending an outpatient clinic and taking anticonvulsants had no sign of rickets. Causative factors for the development of rickets were evaluated. Administration of anticonvulsive drugs depressed the serum 25-hydroxyvitamin D (25-OHD) level, but this was not the major factor in the development of rickets. Vitamin D intake seemed to be about average in these patients and its supplementation increased their serum 25-OHD level. This serum 25-OHD level was not maintained by supplemental vitamin D, unless the children were exposed to sunlight. These results indicate that although several factors--such as anticonvulsants, low vitamin D intake, and inactivity--are concerned in the development of rickets, the main cause is lack of sun in institutionalised handicapped children.     

Vitamin D-dependent rickets type I and type II

Two distinct hereditary defects, vitamin D-dependent rickets type I (VDDR I) and type II (VDDR II), have been recognized in vitamin D metabolism. VDDR I is suggested to be a deficiency of the renal 25-hydroxyvitamin D (25(OH)D)-1α-hydroxylase. Muscle weakness and rickets are the prominent clinical findings. A normal physiologic dose of 1α-hydroxyvitamin D₃ and 1,25-dihydroxyvitamin D₃ is sufficient to maintain remission of rickets in this disorder. VDDR II consists of a spectrum of intracellular vitamin D receptor (VDR) defects and is characterized by the early onset of severe rickets and associated alopecia. This can be attributed to mutations in the VDR gene. Massive doses of vitamin D analogs and calcium supplementation is usually required for the treatment; however, the response to therapy is sometimes variable.     

Vitamin D receptor defects: the story of hereditary resistance to vitamin D

Vitamin D, synthesized in the epidermis in response to UV radiation, is devoid of any biological activity. The hormonal activity is due to its metabolite, 1 alpha, 25-dihydroxyvitamin D, named calcitriol. The actions of calcitriol are mediated by the vitamin D receptor, VDR, a member of the nuclear receptor family. The clinical presentation of hypocalcaemia, secondary hyperparathyroidism, early onset rickets in the presence of normal levels of serum 25-hydroxyvitamin D and markedly elevated serum levels of calcitriol is indicative of hereditary vitamin D resistant rickets, HVDRR. HVDRR is a recessive autosomal disorder that has been described in approximately 60 unrelated families. Dermal fibroblasts and peripheral blood lymphocytes can serve as target organ models to evaluate the interaction of calcitriol and its effector system. Failure of calcitriol to induce the enzyme 25-hydroxyvitamin D3 24 hydroxylase in fibroblasts or to inhibit lymphocyte mitogenesis can serve as the diagnosis for HVDRR Transfection studies employing site directed mutagenesis to mimic the natural mutations in VDR, have identified mutations that interfere with the major events in VDR signaling: hormone binding; heterodimerization with RXR; binding to vitamin D response elements in the promoters of target genes; and interaction with co- activators. Interference with one or more of these steps results in the clinical syndrome of HVDRR.     

Effects of early vitamin D deficiency rickets on bone and dental health,growth and immunity

Vitamin D deficiency is associated with adverse health outcomes, including impaired bone growth, gingival inflammation and increased risk for autoimmune disease, but the relationship between vitamin D deficiency rickets in childhood and long‐term health has not been studied. In this study, we assessed the effect of early vitamin D deficiency on growth, bone density, dental health and immune function in later childhood to determine if children previously diagnosed with rickets were at greater risk of adverse health outcomes compared with healthy children. We measured serum 25‐hydroxyvitamin D, calcium, parathyroid hormone, bone mineral density, anthropometric measures, dietary habits, dental health, general health history, and markers of inflammation in 14 previously diagnosed rickets case children at Children's Hospital Oakland Research Center. We compared the findings in the rickets cases with 11 healthy children selected from the population of CHO staff families. Fourteen mothers of the rickets cases, five siblings of the rickets cases, and seven mothers of healthy children also participated. Children diagnosed with vitamin D deficiency rickets had a greater risk of fracture, greater prevalence of asthma, and more dental enamel defects compared with healthy children. Given the widespread actions of vitamin D, it is likely that early‐life vitamin D deficiency may increase the risk of disease later in childhood. Further assessment of the long‐term health effects of early deficiency is necessary to make appropriate dietary recommendations for infants at risk of deficiency.     

维生素D受体基因多态性与维生素D缺乏性佝偻病遗传关联性Meta分析

目的:评价维生素D受体（VDR）基因多态性与维生素D缺乏性佝偻病(佝偻病)的遗传关联性。方法:制定原始文献的纳入标准及检索策略,检索PubMed、Springer、Science Direct、Web of Science、中国期刊全文数据库、维普中文科技期刊数据库和万方数据库,收集VDR基因FokⅠ、ApaⅠ、BsmⅠ和TaqⅠ位点多态性与佝偻病相关性的病例对照研究,以佝偻病患儿为病例组。依据NHI NHGRI研究工作组2007年制定的遗传关联性研究报告规范为基础,并依据相关文献选取其中的14条标准用于评价文献偏倚。以基因型频率为指标,提取数据后先确定最佳遗传模型,采用Stata 11.0软件进行Meta分析,计算合并的OR值及其95％CI。结果:19篇病例对照研究进入Meta分析。①FokⅠ位点采用共显性模型（FF基因型 vs ff基因型;FF基因型 vs Ff基因型）分析,病例组704例,对照组596例。Meta分析结果显示,亚洲人群FF基因型较ff基因型（OR=4.59,95%CI：2.98~7.07）和Ff基因型(OR=2.58,95%CI：1.79~3.73)患佝偻病的风险显著增加;高加索人群FokⅠ位点与佝偻病无显著关联性（FF基因型 vs ff基因型,OR=2.50,95%CI：0.76~8.19;FF基因型 vs Ff基因型,OR=1.18,95%CI：0.66~2.10）;非洲人群FF基因型较ff基因型患佝偻病的风险显著增加（OR=5.81,95%CI：1.21~27.98）。②ApaⅠ位点采用显性模型（AA+Aa基因型 vs aa基因型）分析,病例组338例,对照组459例。亚洲人群和非洲人群ApaⅠ位点与佝偻病均无显著关联性,OR分别为1.04（95%CI：0.72~1.49）和0.98（95%CI：0.57~1.71）;高加索人群AA+Aa基因型患佝偻病的风险增高（OR=5.50,95%CI：1.22~24.75）。③BsmⅠ位点采用显性模型（bb基因型 vs Bb+BB基因型）分析,病例组822例,对照组736例。亚洲人群BsmⅠ位点bb基因型较Bb+BB基因型患佝偻病的风险降低(OR=0.46,95%CI：0.23~0.92),非洲人群BsmⅠ位点与佝偻病无显著关联性（OR=1.65,95%CI：0.95~2.88）。④TaqⅠ位点采用隐性模型（TT基因型 vs Tt+tt基因型）分析, 病例组519例,对照组513例。亚洲人群（OR=1.22,95%CI：0.82~1.82）、高加索人群（OR=0.91,95%CI：0.35~2.35）和非洲人群（OR=1.18,95%CI：0.68~2.05）TaqⅠ位点与佝偻病无显著关联性。结论:现有证据表明,亚洲人群FokⅠ位点FF基因型为患佝偻病的危险因素,而BsmⅠ位点bb基因型为佝偻病轻微的保护因素,尚不能认为ApaⅠ和TaqⅠ位点与佝偻病有关联性;由于高加索人群和非洲人群研究较少,VDR基因多态性与佝偻病的关联性尚不明确。     

A case of dilated cardiomyopathy due to nutritional vitamin D deficiency rickets

Vitamin D deficiency rickets was detected as the cause in a nine-month-old girl with dilated cardiomyopathy and signs of congestive heart failure. The patient responded to calcium and vitamin D supplementation promptly and left ventricular systolic functions normalized at the 3rd month of treatment. Nutritional rickets must be remembered in etiological assessment of dilated cardiomyopathy among infants living in regions in which nutritional rickets is still common.     

Rickets

Worldwide, rickets is the most common form of metabolic bone disease in children. Despite the concept that it is a rare disease, it is on the increase in many regions, including Western Europe and the USA, and in many ethnic subgroups that have immigrated to temperate regions. Vitamin D deficiency is the main cause of rickets, though nutritional deficiency of calcium and phosphorous generates the same clinical picture. Rickets also occurs when the metabolites of vitamin D are deficient. This may be due to an inherited cause or secondary to disorders of the gut, pancreas, liver or kidney from disruption of vitamin D metabolism.     

Nutritional rickets around the world: causes and future directions

INTRODUCTION: Nutritional rickets has been described from at least 59 countries in the last 20 years. Its spectrum of causes differs in different regions of the world. METHODS: We conducted a systematic review of articles on nutritional rickets from various geographical regions published in the last 20 years. We extracted information about the prevalence and causes of rickets. RESULTS: Calcium deficiency is the major cause of rickets in Africa and some parts of tropical Asia, but is being recognised increasingly in other parts of the world. A resurgence of vitamin D deficiency has been observed in North America and Europe. Vitamin D-deficiency rickets usually presents in the 1st 18 months of life, whereas calcium deficiency typically presents after weaning and often after the 2nd year. Few studies of rickets in developing countries report values of 25(OH)D to permit distinguishing vitamin D from calcium deficiency. CONCLUSIONS: Rickets exists along a spectrum ranging from isolated vitamin D deficiency to isolated calcium deficiency. Along the spectrum, it is likely that relative deficiencies of calcium and vitamin D interact with genetic and/or environmental factors to stimulate the development of rickets. Vitamin D supplementation alone might not prevent or treat rickets in populations with limited calcium intake.     

佝偻病维生素D受体基因多态性与25-羟维生素D3相关性

目的：研究1~3岁佝偻病患儿中维生素D受体基因多态性FokⅠ位点与佝偻病相关性,初步探讨维生素D受体基因多态性FokⅠ位点在佝偻病发病中的作用。方法：病例组（佝偻病患儿）62例与对照组（正常健康儿童）60例,用ELISA方法检测血清25-羟维生素D3水平,比较两组之间血清25-羟维生素D3水平。用聚合酶链反应-限制性片段长度多态性（PCR-RFLP）检测病例组和对照组维生素D受体基因多态性FokⅠ位点,比较两组之间基因型和等位基因分布频率。结果病例组血清25-羟维生素D3水平较对照组明显降低,差异有统计学意义（9.1±4.1 ng/mL vs 16.1±6.9 ng/mL;P＜0.05）。维生素D受体基因多态性FokⅠ位点病例组FF基因型明显高于对照组（53% vs 25%）,基因型分布频率差异有统计学意义（χ2=10.221,P＜0.05）,病例组F等位基因频率明显高于对照组（73% vs 57%）,等位基因分布频率差异有统计学意义（χ2=7.511,P＜0.05）。结论维生素D受体基因多态性FokⅠ位点与佝偻病有相关性,提示其在佝偻病遗传易感性方面起重要作用。［中国当代儿科杂志,2010,12（7）：544-546］     

Persisting vitamin D deficiency in the Asian adolescent.

A study of 221 children admitted to hospital in the course of a year allowed establishment of a reference range for plasma 25-hydroxyvitamin D. None of these children had evidence of biochemical rickets. Most Asian children, however, were vitamin D deficient in comparison, and this deficiency was most noticeable in girls aged 13 to 15 years: biochemical rickets occurred in six per cent of these adolescent Asians. If vitamin D requirements are not met during the physiological growth spurt, permanent pelvic deformity may result. Vitamin D deficiency persisting into pregnancy will adversely affect the infant, producing an increased risk of hypocalcaemic fits, dental enamel hypoplasia, infantile rickets, and reduced postnatal growth. Our data support the need for vitamin D supplementation, and we suggest that annual oral vitamin D supplements in the autumn would alleviate the problem.