遗传性牙本质发育不全Ⅱ型DSPP基因新突变

目的分析我国遗传性牙本质发育不全Ⅱ型(dentinogenesisimperfectatypeⅡ,DGI-Ⅱ)患者DSPP基因突变特征,从分子水平探讨DGI-Ⅱ的发病机制。方法抽提2个汉族遗传性牙本质发育不全Ⅱ型家系患者外周静脉血基因组DNA,应用聚合酶链反应及DNA测序技术,结合序列分析方法,对2个家系共13名家庭成员的DSPP基因1～4号外显子及其邻近序列进行突变分析。结果家系A中的患者在DSPP的第4外显子发生Asn164Tyr突变;家系B的患者在DSPP第4外显子发生Cys159Trp突变。结论这两个突变系是国内外尚未报道的新突变。     

遗传性牙本质发育不全Ⅱ型致病基因的突变检测

目的：对遗传性牙本质发育不全Ⅱ型家系的牙本质涎磷蛋白基因启动子和非高度重复序列编码区进行突变分析,试图在基因水平说明其致病原因。方法：使用PCR技术扩增牙本质涎磷蛋白基因启动子区和非高度重复序列编码区,通过DNA直接测序方法对基因序列进行分析。结果：在牙本质涎磷蛋白启动子区和非高度重复序列编码区未检测到与疾病表型相关的特异性改变。但在牙本质涎蛋白编码区检测到不同个体之间具有多态性。结论：该遗传性牙本质发育不全Ⅱ型家系的牙本质涎磷蛋白基因启动子和非高度重复序列编码区序列未发现导致疾病的突变。     

遗传性乳光牙本质致病基因DSPP的突变分析

目的：就天津地区新发现的一个遗传性乳光牙本质回族家系进行牙本质涎磷蛋白(dentin sialophosphoprotein，DSPP)致病基因的突变检测，以证实是否有新的突变位点，并进一步阐明该病基因型和表型问的相互关系。方法：对该家系中的10名患者和8名正常人提取外周血DNA，针对DSPP基因外显子3和外显子4设计引物，以进行巢氏PCR扩增。PCR扩增产物经直接测序分析，或用限制性内切酶Rsal酶切鉴定。结果：测序结果显示：遗传性乳光牙本质患者DSPP基因外显子3的3658位核苷酸存在C→T的无义突变，该突变使终止密码子提前出现；Rsal酶切分析也证实：10名患者的DSPP基因发生了终止突变，所有患者在该位点均为杂合子。结论：DSPP基因无义突变可能会严重影响DSPP基因的功能，从而导致牙本质发育不全。     

Ⅱ型牙本质发育不全患者DSPP基因突变的研究进展

遗传性牙本质发育不全Ⅱ型是一种常见的常染色体显性遗传性牙本质缺陷病,牙本质涎磷蛋白基因(DSPP)的突变已被证明是其致病原因.现今在DSPP编码区已发现了超过30个突变位点,可分为信号肽编码区突变、牙本质涎蛋白基因(DSP)编码区突变和牙本质磷蛋白基因(DPP)编码区突变等3组,本文对以上各组突变位点及突变机制进行综述...     

牙本质发育不全Ⅱ型的遗传异质性研究

目的：明确牙本质涎磷蛋白(dentin sialophosphoprotein，DSPP)是否为该家系的致病基因，并对该家系做进一步的基因定位研究。方法：通过DNA测序方法对DSPP基因进行突变检测，用位于4q21区域的7个微卫星位点对家系进行遗传连锁分析。结果：测序结果显示DSPP在该家系中不存在突变，基因定位研究表明致病基因在该家系位于IMS1534和DSPP之间。结论：DSPP在该家系不是致病基因，牙本质发育不全Ⅱ型存在遗传异质性。     

牙本质发育异常分类方法进展及相应临床管理策略

位于第4常染色体的牙本质涎磷蛋白(dentin sialophosphoprotein, DSPP)基因是迄今发现的遗传性牙本质发育异常的主要致病基因。根据de La Dure-Molla等提出的新分类, 将由DSPP基因突变引起的主要表现为牙本质发育异常的疾病统称为牙本质发育不全(dentinogenesis imperfecta, DI), 包括Shields分类法的牙本质发育不良Ⅱ型(dentin dysplasia type-Ⅱ, DD-Ⅱ)、牙本质发育不全Ⅱ型(dentinogenesis imperfecta type-Ⅱ, DGI-Ⅱ)和牙本质发育不全Ⅲ型(dentinogenesis imperfecta type-Ⅲ, DGI-Ⅲ)3种疾病。将Shields分类的牙本质发育不良Ⅰ型(dentin dysplasia type-Ⅰ, DD-Ⅰ)称为根部牙本质发育不良(radicular dentin displasia)。本文对遗传性牙本质发育异常的分类方法、临床特征、致病基因的研究进展进行阐述, 根据不同阶段的临床特征, 提出相应的临床管理和治疗策略。     

小鼠牙本质涎磷蛋白基因上游启动子的克隆和序列测定

目的　克隆并测定小鼠牙本质涎磷蛋白(DSPP)基因上游启动子的序列。方法　提取成年Balb/c鼠基因 组DNA,设计引物,通过聚合酶链反应(PCR)得到小鼠牙本质涎磷蛋白基因上游启动子的序列。再将目的片段定向 连入T载体,酶切鉴定并测序。结果　将小鼠牙本质涎磷蛋白基因上游启动子序列分3段克隆,分别得到997 bp、 1 004 bp及674 bp大小的目的片段。连入载体后,酶切结果测定重组质粒成功。其测序结果与小鼠基因组染色体 位置5q21处的相应序列99%一致。结论　成功克隆到牙本质涎磷蛋白基因上游启动子的序列,为进一步研究 DSPP基因的转录调控机制奠定了基础。     

牙本质发育不全的研究进展与治疗策略

牙本质发育不全(dentinogenesis imperfecta,DI)是一种常染色体显性遗传病,根据1973年提出的Shields分类法可分为I、II、III型.I型的致病基因为COL1A1与COL1A2基因;II型与III型的致病基因为牙本质涎磷蛋白(dentin sialophosphoprotein,DSPP...     

DSPP启动子和DPP基因的突变检测

目的：对2个遗传性牙本质发育不全Ⅱ型(DGI—Ⅱ)家系的DSPP启动子和DPP基因编码序列进行突变检测。方法：在DPP两端设计引物拉出DPP全长，以此为模板在DPP序列内部设计引物，同时在DSPP启动子内部设计引物，经PCR(聚合酶链反应)和DNA测序进行突变检测。结果：在DPP内发现插入、缺失等变化，但未找到与表型完全一致的突变。结论：在所测DGI—Ⅱ型家系的DPP编码区及启动子未发现与表型相关的突变。     

遗传性乳光牙本质致病基因DSPP的突变分析

遗传性乳光牙本质又名牙本质发育不全Ⅱ型(dentinogenesisimperfectatypeⅡ ,DGI Ⅱ或DGI1 ) (MIM1 2 5490 )是一种常染色体显性遗传病 ,表现为牙齿结构异常。我们拟就新发现的一个DGI Ⅱ家系进行牙本质涎磷蛋白(dentinsialophosphoprotein ,DSPP)致病基因的突变检测 ,以证实是否有新的突变位点 ,从而进一步阐明该病基因型和表型间的相互关系。一、材料和方法1 .研究对象 :为天津医科大学口腔医院牙体牙髓科发现的一个DGI Ⅱ回族家系 ,可追溯 5代 ,现存活 4代 ,共 31人 ,1 0人受累 ,5例乳光牙表现 ,其他患者已作修复治疗。先证者前…     

Enamel malformations associated with a defined dentin sialophosphoprotein mutation in two families

Dentin sialophosphoprotein (DSPP) mutations cause dentin dysplasia type II (DD-II) and dentinogenesis imperfecta types II and III (DGI-II and DGI-III, respectively). We identified two kindreds with DGI-II who exhibited vertical bands of hypoplastic enamel. Both families had a previously reported DSPP mutation that segregated with the disease phenotype. Oral photographs and dental radiographs of four affected and one unaffected participant in one family and of the proband in the second family were used to document the dental phenotypes. We aligned the 33 unique allelic DSPP sequences showing variable patterns of insertions and deletions (indels), generated a merged dentin phosphoprotein (DPP) sequence that includes sequences from all DSPP length haplotypes, and mapped the known DSPP mutations in this context. Analyses of the DSPP sequence changes and their probable effects on protein expression, as well as published findings of the dental phenotype in Dspp null mice, support the hypothesis that all DSPP mutations cause pathology through dominant-negative effects. Noting that Dspp is transiently expressed by mouse pre-ameloblasts during formation of the dentino-enamel junction, we hypothesize that DSPP dominant-negative effects potentially cause cellular pathology in pre-ameloblasts that, in turn, causes enamel defects. We conclude that enamel defects can be part of the dental phenotype caused by DSPP mutations, although DSPP is not critical for dental enamel formation.     

Genetic linkage of the dentinogenesis imperfecta type III locus to chromosome 4q.

Dentinogenesis imperfecta type III (DGI-III) is an autosomal-dominant disorder of dentin formation which appears in a tri-racial southern Maryland population known as the "Brandywine isolate". This disease has suggestive evidence of linkage to the long arm of human chromosome 4 (LOD score of 2.0) in a family presenting with both juvenile periodontitis and DGI-III. The purpose of this study was to screen a family presenting with only DGI-III to determine if this locus was indeed on chromosome 4q. Furthermore, we wanted to determine if DGI-III co-localized with dentinogenesis imperfecta type II (DGI-II), which has been localized to 4q21-q23. Therefore, a large kindred from the Brandywine isolate was identified, oral examination performed, and blood samples collected from 21 family members. DNA from this family was genotyped with 6 highly polymorphic markers that span the DGI-II critical region of chromosome 4q. Analysis of the data yielded a maximum two-point LOD score of 4.87 with a marker for the dentin matrix protein 1 (DMP1) locus, a gene contained in the critical region for DGI-II. Our results demonstrated that the DGI-III locus is on human chromosome 4q21 within a 6.6 cM region that overlaps the DGI-II critical region. These results are consistent with the hypothesis that DGI-II is either an allelic variant of DGI-III or the result of mutations in two tightly linked genes.     

Phenotypic variation in dentinogenesis imperfecta/dentin dysplasia linked to 4q21

Dentinogenesis imperfecta (DGI) and dentin dysplasia (DD) are allelic disorders that primarily affect the formation of tooth dentin. Both conditions are autosomal-dominant and can be caused by mutations in the dentin sialophosphoprotein gene (DSPP, 4q21.3). We recruited 23 members of a four-generation kindred, including ten persons with dentin defects, and tested the hypothesis that these defects are linked to DSPP. The primary dentition showed amber discoloration, pulp obliteration, and severe attrition. The secondary dentition showed either pulp obliteration with bulbous crowns and gray discoloration or thistle-tube pulp configurations, normal crowns, and mild gray discoloration. Haplotype analyses showed no recombination between three 4q21-q24 markers and the disease locus. Mutational analyses identified no coding or intron junction sequence variations associated with affection status in DMP1, MEPE, or the DSP portion of DSPP. The defects in the permanent dentition were typically mild and consistent with a diagnosis of DD-II, but some dental features associated with DGI-II were also present. We conclude that DD-II and DGI-II are milder and more severe forms, respectively, of the same disease.     

一个掌跖角化-牙周破坏综合征患者家系组织蛋白酶C基因突变分析

目的 对一个掌跖角化-牙周破坏综合征（PLS）患者及其家系组织蛋白酶C基因（CTSC）突变位点进行分析,探讨PLS的分子致病机制。方法 提取1例PLS先证者及其直系血亲（父母、弟弟）的基因组DNA,应用聚合酶链反应和DNA直接测序技术分析先证者及其直系血亲CTSC基因的突变情况。结果 PLS先证者CTSC基因存在复合型杂合突变。先证者位于外显子6的第800位碱基发生了一个杂合错义突变,该碱基对中的碱基T被C取代（c.800T>C）,其编码的氨基酸由亮氨酸改变为脯氨酸（p.L267P）;位于外显子7的第1015位碱基发生了一个杂合错义突变,该碱基对中的碱基C被T取代（c.1015C>T）,其编码的氨基酸由精氨酸改变为半胱氨酸（p.R339C）。其中,c.800T>C来自母亲,c.1015C>T来自父亲,弟弟的CTSC基因未见突变。结论 PLS的临床表征与CTSC基因突变有关。     

Evidence of Intrafamilial Variability of CBFA1/RUNX2 Expression in Cleidocranial Dysplasia – a Family Study

AIM: To investigate the phenotypical expression of an identical mutation of the CBFA1/RUNX2 gene within a family with cleidocranial dysplasia. PATIENTS AND METHOD: A five-member family underwent clinical examination. Two members, father and son, showed dissimilar symptoms of cleidocranial dysplasia. The two affected patients were examined for syndrome-typical symptoms, and the genotype was determined by molecular-genetic analysis. RESULTS: In both patients an identical missense mutation (G146R) in exon 2 of the CBFA1/RUNX2 gene was identified. In father and son the dental disturbances were similarly clearly expressed. However, the craniofacial skeleton of the son exhibited fewer dysostotic ossification features than that of the father. In the three clinically healthy family-members no mutation of the CBFA1/RUNX2 gene was found. CONCLUSION: In two patients with cleidocranial dysplasia an identical missense mutation in the CBFA1/RUNX2 gene leading to a divergent craniofacial phenotype was determined. The results indicate marked variability in the phenotypical expression of CBFA1/RUNX2 mutations.     

Splicing site mutations in dentin sialophosphoprotein causing dentinogenesis imperfecta type II

Dentinogenesis imperfecta (DGI) type II (OMIM # 125490) is an inherited disorder affecting dentin. Defective dentin formation results in discolored teeth that are prone to attrition and fracture. To date, several mutations have been described in the dentin sialophosphoprotein (DSPP) gene, causing DGI types II and III and dentin dysplasia type II. DSPP encodes two proteins: dentin sialoprotein (DSP) and dentin phosphoprotein (DPP). Here, we describe a mutational analysis of DSPP in seven Finnish families with DGI type II. We report two mutations and five single nucleotide polymorphisms. In one family we found a mutation that has been described earlier in families with different ethnicity, while in six families we found a novel g.1194C>A (IVS2-3) transversion. Bioinformatic analysis of known DSPP mutations suggests that DGI type II is usually caused by aberration of normal splicing.     

The non-collagenous dentin matrix proteins are involved in dentinogenesis imperfecta type II (DGI-II)

Dentinogenesis Imperfecta type II (DGI-II) is a localized form of mesodermal dysplasia of the dentin affecting both the primary and permanent dentitions. This is an autosomal-dominant disease in which there is a disorder in dentin mineralization. Several studies have localized DGI-II to human chromosome 4 in the region 4q 12-21. Many ECM genes-such as OPN, DMP1, DMP2, DMP3 (DSPP), and BSP-have been mapped to the same locus. Biochemical studies indicated that dentin phosphophoryn (DMP2) might be a candidate gene in DGI-II. In this study, we have used histological and RFLP analyses of tissues from a DGI-II-affected patient, as compared with two normal controls, to determine if DMP1, 2, or 3 was linked to DGI-II. The histology of the affected tooth was very different in the DGI-II patient as compared with the normals. In particular, the dentinal tubules in the DGI-II patient were very irregular, which could be the result of perturbations in the process of dentin formation. Patient and control DNA samples were digested with EcoRI or PstI and Southern-hybridized with the DMP1, DMP2, and DMP3 cDNAs. Few differences in the restriction pattern were observed between affected and normal samples for DMP1 and DMP3-3' region (phosphophoryn-like sequences) probes. On the other hand, DMP2 showed a dramatic shift in the restriction pattern in DGI-II. This study suggests that the different restriction enzyme digestion profiles of the DNA from the DGI-II patient, as probed by DMP2, might be related to the defective mineralization of dentin in DGI-II.     

A novel FGFR2 gene mutation in Crouzon syndrome associated with apparent nonpenetrance.

OBJECTIVE: To determine whether specific mutations within the fibroblast growth factor receptor 2 (FGFR2) gene that are associated with Crouzon syndrome can be present in an individual who had been assumed to be "clinically normal." METHODS: Most mutations responsible for Crouzon syndrome occur in exons IIIa (U) or IIIc (B) of the FGFR2 gene, which facilitates allelotyping using polymerase chain reaction (PCR)-mediated mutation analysis. Once a specific mutation was identified in the index case, remaining affected family members and "clinically normal" first-degree relatives were analyzed in order to correlate genotype with phenotype. RESULTS: A novel missense mutation--a G to T transversion--involving the first base of codon 362 was identified in all Crouzon syndrome-affected family members and in one "clinically normal"-appearing parent following DNA sequencing of exon B of the FGFR2 gene and specific BstNI restriction fragment length polymorphism. Pattern profile analysis demonstrated a consistent collection of abnormal cephalometric measurements in the Crouzon-affected family members and, to a lesser degree, in the "clinically normal" parent. CONCLUSION: We have identified a novel missense mutation in the FGFR2 gene that predicts an Ala362Ser substitution shared by all family members affected by Crouzon syndrome and by a "clinically normal"-appearing father. These data support nonpenetrance of Crouzon syndrome when the diagnosis is based on clear clinical findings. Only through cephalometry was there an indication of minimal expression of Crouzon syndrome in the "clinically normal"-appearing father.