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。

Association of the vitamin D receptor gene start codon polymorphism with vitamin D deficiency rickets

OBJECTIVE: Vitamin D deficiency rickets often causes growth retardation, impaired bone formation and hypocalcemia in children. It is well known that rickets is mainly caused by vitamin D deficiency, but whether there is hereditary susceptibility of children to develop vitamin D deficiency rickets is unknown. Vitamin D receptor (VDR) gene has been used as one of genetic markers in studying the metabolic diseases of bone. The present study aimed to explore the hereditary susceptibility of children to develop rickets through studying the association between VDR gene start codon polymorphism and vitamin D deficiency rickets, METHODS: The subjects were selected from Kunming city, every subject was of Han ethnic group. The subjects were composed of two groups, the patient group consisted of 48 children with active vitamin D deficiency rickets which was diagnosed clinically and confirmed radiologically; the control group was composed of 92 normal children. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), DNA sequence analysis and genetic analysis methods were used. A restriction fragment length polymorphism in the start codon of VDR gene (FokI) was tested in both groups. RESULTS: VDR gene start codon polymorphism was tested successfully for every subject. Frequencies of FF, Ff and ff genotypes were 46%, 33% and 21% in the rickets group, and 22%, 52% and 26% in the control group, respectively. A significant difference was found in the frequency distribution of VDR genotype between two groups (chi(2) = 8.912, P = 0.012). In the patient group, Ff and ff genotypes were less common than control group, but the FF genotype was more common than control group (OR = 3.046), indicating that FF genotype may be significantly associated with vitamin D deficiency rickets. Moreover, VDR allele frequencies of FokI polymorphism also showed significant difference between the two groups (chi(2) = 5.451, P = 0.020), F alleles were more common in patient group than in control group. DNA sequence analysis identified that the start codon of F allele was mutated from ATG to ACG. CONCLUSION: There is an association between VDR gene start codon polymorphism and vitamin D deficiency rickets. This study suggested the possibility that VDR gene polymorphism might be important in determining an individual's susceptibility to development of vitamin D deficiency rickets.