先天性牙发育不全WNT6基因突变的新位点

目的 探讨先天性牙发育不全病例与相关基因突变可能存在的联系,为疾病的早期诊断提供参考。方法 通过收集1例罕见先天性牙发育不全病例的临床和影像学资料,评估牙齿的形态、数量以及全身健康状况;采集患者静脉外周血,对与牙齿发育紧密关联的PAX9和MSX1基因双向测序;进行全外显子测序,筛查与牙发育异常相关的其他突变位点,对先证者儿子进行新发现突变位点的Sanger测序;通过模拟测算工具和体外细胞转染实验评估突变对基因表达的影响。结果 患者的临床特征是先天性右下颌单侧第一磨牙缺失,第二磨牙为单根,且伴有右下第二前磨牙多生。在PAX9和MSX1基因测序中发现,PAX9基因中c.717C>C/T为同义突变,MSX1基因中c.119C>G为错义突变,Polyphen预测为“良性”。全外显子测序发现WNT6基因的1个全新突变位点,内含子3中的c.637-7 C>A突变,经MAXENT预测,可能影响mRNA的剪切,且先证者及其儿子均携带该突变;细胞转染实验发现,该突变对WNT6基因的mRNA剪切没有影响。结论 单核苷酸多态性之间的相互作用可能与先天性牙发育异常相关。     

多数牙先天缺失可能与MSX1上的3个SNPs相关

目的:探讨多数牙先天缺失患者的MSXl基因突变位点.方法:从4个多数牙先天缺失患者与家庭部分成员、1个唇腭裂并发少数牙先天缺失的患者、1个牙列完整的对照儿童共14人的静脉血中提取DNA,在MSXl基因内设计引物,采用PCR方法扩增MSXl基因外显子1、2的编码区,而后对外显子1、2的PCR纯化产物测序,结合系游进行序列比对分析.结果:发现3个可能的单核苷酸多态性位点(single nucleotide pol-ymorphisms,SNPs).这3个SNPs均位于外显子1中,且来自不同家系的3个患者在这3个位点上同时出现杂合突变.其中,311位点由G变A,对应的密码子由编码甘氨酸的GGC变为编码天门冬氨酸的GAC,发生了错义突变;402位点由C变A,对应的密码子由CCC变为CCA,但仍编码脯氨酸,属同义突变;458位点由C变T,对应的密码子由编码丙氨酸的GCC变为编码缬氨酸的GTC,发生了错义突变.结论:多数牙先天缺失可能与MSX1基因上该3个单核苷酸多态性位点有关.     

2例多数牙先天缺失患儿及其父母的Pax9基因突变检测

目的:探讨多数牙先天缺失患者的基因突变位点.方法:从两例多数牙先天缺失患者与家庭成员的静脉血中提取DNA,在Pax9基因内设计引物,采用PCR方法扩增Pax9基因的外显子2、3、4,而后通过对分段PCR纯化产物的测序,并结合系谱进行单核甘酸多态性分析.结果:外显子3的第88、89位点上发现两个单核甘酸多态性位点(single nucleotide polymorphisms,SNPs),其中第88位为C变为T,第99位为G变为C,前者是同义突变,后者是错义突变,由丙氨酸变为脯氨酸.结论:多数牙先天缺失可能与Pax9基因外显子3的第88、89位点上的两个SNPs有关.     

非综合征型先天性多数牙缺失1例

先天性牙齿缺失是牙齿数目异常的一种,分为个别、多数和全部牙齿先天缺失。多数牙先天缺失常为综合征的表现之一或为一种独立的疾病,较为少见。伴有先天缺牙的综合征以Rieger综合征、外胚叶发育不全、EEC综合征等常见。病因不明,通常认为是环境因素和遗传因素参与,以遗传因素为主。有研究认为,成对盒基因9(PAX9)和肌节同源盒基因1(MSX1)分别与前磨牙、磨牙的缺失有关。多数牙齿先天缺失可造成错畸形,治疗时需全面诊断,多学科咨询以利于确定长期治疗的目标。     

PAX9基因上新近发现的一个单核苷酸多态性位点的SNP分析

目的:研究位于PAX9基因外显子3的第89位点上的SNP与多数牙先天缺失的相关性.方法:分别从11名多数牙先天缺失病人,5名少数牙先天缺失病人和38名正常对照者的静脉血样品中提取DNA.采用TaqMan-MGB探针技术对该SNP位点进行单核苷酸多态性研究,利用软件对实验结果进行SNP分型,并行统计分析.结果:突变为纯合子C/C的绝大多数表现为先天缺牙(多数牙先天缺失5例,少数牙先天缺失2例,正常1例).但31例杂合子中只有7例表现为先天缺牙(多数牙先天缺失6例,少数牙先天缺失1例).13例野生型纯合子只有2例表现为少数牙先天缺失,11例完全正常.统计结果表明该位点与多数牙先天缺失相关(P<0.001).结论:多数牙先天缺失可能与PAX9基因外显子3的第89位点上的SNP有关.     

中国先天性缺失牙患者PAX9基因的新突变

目的 探讨我国先天性缺失牙患者PAX9基因突变的特点，为该病发病的分子机制研究提供依据。方法 应用聚合酶链反应．单链构象多态性(PCR-SSCP)分析方法，对4个常染色体显性遗传少牙畸形家系(共45名成员，22例患者)中的13例患者和9名健康成员、16例散发性牙齿发育不全患者以及196名健康对照者的PAX9基因进行研究。结合DNA序列分析方法，对发现异常SSCP条带的患者进行突变分析。结果 2个少牙畸形家系(家系A和家系B)的先证者出现异常SSCP条带，家系A和家系B内患者均出现与各自先证者相同的异常SSCP条带。经过DNA序列分析，发现PAX9基因第2外显子的2个新突变：碱基插入(109InsG)导致的移码突变，碱基置换(c139T)导致的错义突变。其余家系患者、散发性患者均未发现异常SSCP条带。结论 109InsG和C139T突变扩大了先天性缺失牙患者的PAX9基因突变谱，为我国先天性缺失牙的基因诊断提供依据。     

Van der Woude综合征家系先天缺牙患者MSX1基因突变的检测

目的探讨MSX1基因与Van der Woude综合征(VWS)家系中缺牙的关系。方法从VWS家系9中伴发缺牙患者2人及家系正常成员2人、60个牙列完整的健康者共64人的静脉血中提取DNA,设计MSX1基因引物,采用PCR方法扩增MSX1基因外显子1、2的编码区,而后对外显子1、2的PCR纯化产物测序,进行序列比对分析。结果 VWS家系9两个缺牙患者MSX1基因中有ivs2+68 C>T多态;伴IRF6基因突变的VWS患者缺牙较多。结论 VWS家系9中先天缺牙患者的牙先天缺失与MSX1基因的ivs2+68 C>T多态可能相关。     

非综合征型先天缺牙致病基因和分子机制的研究进展

先天缺牙是牙齿发育过程中常见的牙数目发育异常,对患者的颌面部发育及美观和咀嚼功能产生严重的影响。根据有无伴发全身症状,先天缺牙可分为综合征型先天缺牙与非综合征型先天缺牙。近几年发现新的相关基因和新的突变位点及分子机制已成为目前非综合征型先天缺牙基因研究的主要方向。本文通过对近年来文献的回顾,对与非综合征型先天缺牙主要相关的Wnt/β-catenin信号通路、TGF-β/BMP信号通路、PAX9基因和MSX1基因、EDA/EDAR/NF-κb信号通路的分子机制以及相互调节的紧密联系进行综述,为未来先天缺牙的防治提供了新的理论基础。非综合征型先天缺牙致病基因的分子机制的研究目前甚少,对于其机制的精准探索将成为先天缺牙未来主要的研究方向之一。     

单纯型多数牙缺失的PAX9基因新突变一例

苏州大学附属第二医院口腔中心收治单纯型多数牙缺失1例,患者先天缺失恒牙16颗,其他系统无异常,其母与患者有相似表型。收集患者、患者父母及外祖父母外周血,提取DNA,采用PCR结合直接测序进行PAX9、MSX1、WNT10A、WNT10B、AXIN2和EDA等候选基因突变检测,PCR-Sanger测序发现PAX9基因的起...     

非综合征性先天缺牙相关基因的研究进展

先天缺牙是牙发育过程中的数目异常,包括个别牙先天缺失、多数牙先天缺失和先天无牙症。先天缺牙根据是否有伴发症状可分为综合征性和非综合征性,表现为常染色体的显性或隐性遗传、X-连锁遗传特性等。先天缺牙可以是有家族遗传史的,也可以是散发的。本文就与非综合征性先天缺牙有关的配对盒基因-9、肌节同源盒基因-1、轴抑制基因-2和外...     

Sequence analysis of PAX9, MSX1 and AXIN2 genes in a Chinese oligodontia family

Objectives

The goal of our research was to look into the clinical traits and genetic mutations in nonsyndromic oligodontia in a Chinese family and to gain insight into the role of mutations of PAX9, MSX1 and AXIN2 in oligodontia phenotypes.

Materials and methods

6 subjects from a family underwent complete oral examination, including panoramic radiographs. Retrospective data were reviewed and blood samples were collected. PCR primers for PAX9, MSX1, and AXIN2 were designed through the Oligo Primer Analysis Software. PCR products were purified and sequenced using the BigDye Terminator Kit and analysed by the 3730 DNA Analyzer.

Results

The proband missed 4 permanent canines, 2 permanent maxillary lateral incisors, 2 permanent mandibular lateral incisors, and 2 permanent mandibular central incisors, whilst his maternal grandfather lacked only 2 permanent mandibular central incisors. Moreover, the size of some permanent teeth appeared smaller than normal values of crown width of Chinese people. Oligodontia and abnormalities of teeth were not present in other family members. Radiographic examination showed that the proband and the rest of family members retained all germs of the third molars. There was one known mutation A240P (rs4904210) of PAX9 in the coding region in the proband and the maternal family members (II-2, II-3, and II-4), which possibly contributed to structural and functional changes of proteins. No mutations were identified in MSX1 and AXIN2.

Conclusions

Our findings may imply that the PAX9 A240P mutation is a risk factor for oligodontia in the Chinese population. A240P is likely to be a genetic cause of oligodontia though previous literature suggested it as a polymorphism only.     

Novel mutation of the initiation codon of PAX9 causes oligodontia

Tooth development is under strict genetic control. Oligodontia is defined as the congenital absence of 6 or more permanent teeth, excluding the third molar. The occurrence of non-syndromic oligodontia is poorly understood, but in recent years several cases have been described where a single gene mutation is associated with oligodontia. Several studies have shown that MSX1 and PAX9 play a role in early tooth development. We screened one family with non-syndromic oligodontia for mutations in MSX1 and PAX9. The pedigree showed an autosomal-dominant pattern of inheritance. Direct sequencing and restriction enzyme analysis revealed a novel heterozygous A to G transition mutation in the AUG initiation codon of PAX9 in exon 1 in the affected members of the family. This is the first mutation found in the initiation codon of PAX9, and we suggest that it causes haploinsufficiency.     

Identification of a novel mutation in the PAX9 gene in a family affected by oligodontia and other dental anomalies

The objective of the present work was to study the phenotype and the genotype of three generations of a family affected by oligodontia and other dental anomalies. These family members also presented systemic conditions such as hypercholesterolemia, hypothyroidism, diabetes mellitus, scoliosis, and congenital cardiovascular anomalies. Clinical evaluation, panoramic radiographs, and anamnestic data were used for dental analysis. DNA extraction was carried out from gum samples or buccal swabs. A mutation was identified in six subjects across three generations affected by oligodontia, as well as different phenotypical manifestations, both systemic and oral. The previously undescribed PAX9 mutation was observed in the paired box (exon 2); this was a heterozygote transition of C175 to T, implying the change of arginine 59 for a termination codon. These results strongly suggested that the identified mutation was the etiological cause of the oligodontia. However, in two family members affected by both hypodontia and peg-shaped upper lateral incisors, no mutations in the PAX9 and MSX1 genes were identified. This fact underscores the importance that other presently unknown genes and developmental factors have in tooth development and in the etiology of dental anomalies.     

Identification of a novel missense mutation of MSX1 gene in Chinese family with autosomal-dominant oligodontia

OBJECTIVES: Oligodontia is defined as the congenital absence of 6 or more permanent teeth excluding the third molar. The occurrence of non-syndromic still remains poorly understood, but in recent years some cases have been reported where mutations or polymorphisms of PAX9 and MSX1 had been associated with non-syndromic oligodontia. The objective of the present work was to study the phenotype and genotype of three generations of a Han Chinese family affected by non-syndromic autosomal-dominant oligodontia. DESIGN: We examined all individuals of the oligodontia family by clinical and radiographic examinations. Based on clinical manifestations, candidate genes MSX1 and PAX9 were picked up to analyse and screen mutations. RESULTS: Dental evaluation showed that the most commonly missing teeth are the mandibular second premolars, followed by the maxillary second premolars and maxillary lateral incisors, and subsequently the maxillary first premolars. The probability of missing a particular type of tooth is not always bilaterally symmetrical, and differences exist between maxilla and mandible. PCR-SSCP analysis and DNA sequencing revealed a novel missense mutation c.662C>A in a highly conserved homeobox sequence of MSX1 and a known polymorphisms c.347C>G. CONCLUSION: Our finding suggests the missense transversion (c.662C>A) and the polymorphisms (c.347C>G) may be responsible for oligodontia phenotype in this Chinese family.     

PAX9基因在2个新疆维吾尔族非综合征型先天缺牙家系中的表达

目的　通过对新疆维吾尔族非综合征型先天缺牙患者PAX9基因突变的检测,为维吾尔族该病发病的分子机制提供依据。方法　采集2个新疆维吾尔族非综合征型先天缺牙家系颊黏膜拭子,提取DNA,采用聚合酶链反应技术结合DNA双向测序技术对患者DNA进行检测。结果　PAX9基因外显子3的85、86位点检测出两个单核苷酸多态性（single nucleotide polymorphisms,SNPs）位点。结论　PAX9基因外显子3的85、86位点的改变可能与新疆维吾尔族非综合征型先天缺牙的发生有关。     

A novel nonsense mutation in PAX9 is associated with marked variability in number of missing teeth

Tooth development is under strict genetic control. During the last decade, studies in molecular genetics have led to the identification of gene defects causing the congenital absence of permanent teeth. Analyses of PAX9 and MSX1 in nine families with hypodontia and oligodontia revealed one new PAX9 mutation. A LOD score of Z = 1.8 (theta = 0.0) was obtained for D14S75 close to PAX9 in one three-generation family, and sequencing of the gene identified the nonsense mutation c.433C>T. The mutation results in a truncated PAX9 protein containing the paired domain region as a result of the Q145X stop mutation. The family showed a marked phenotypic variability in the number of missing teeth, ranging from 2 to 15 missing teeth. The highest frequency of missing teeth was found for second molars followed by second premolars.