遗传性牙本质发育不全Ⅱ型的疾病基因研究进展

遗传性牙本质发育不全Ⅱ型(dentinogenesis imperfecta,typeⅡ,DG I-Ⅱ)是一种常染色体显性遗传病,疾病基因定位于人类染色体4q21,目前的研究发现患者牙本质唾液酸焦磷酸蛋白基因(dentin sialophosphoprote in,DSPP)有突变,但存在遗传异质性。笔者对DG I-II疾病候选基因及DSPP的突变进行了综述。     

牙本质发育不全的硬组织研究与进展◆

背景：牙本质发育不全是一种牙本质发育异常的常染色体显性遗传病,目前的研究大多集中在致病基因和临床治疗上,硬组织方面的研究相对较少。 目的：就牙本质发育不全的硬组织研究进展做一综述。 方法：以“牙本质发育不全,表面形态,动物模型,釉牙本质界,牙本质小管”为关键词,应用计算机检索1999/2011 CNKI数据库、PubMed数据库,OVID数据库。 结果与结论：多数学者研究发现牙本质发育不全的釉质结构正常,病变主要表现在釉牙本质界和牙本质。其釉牙本质界大多表现为直线型外观,牙本质结构紊乱,钙化不规则,牙本质小管数目减少,胶原纤维形态和排列异常。这些异常结构的成因尚不清楚,有待深入研究。     

性发育异常的细胞遗传学及分子遗传学研究

目的：对530例性发育异常患者进行细胞、分子还传学检查分析以探讨性发育不良的原因及发病机制。方法：常规外周血淋巴细胞染色体制备及显带技术。聚合酶链式反应（PCR）检测SRY基因（sex-determiningregiononY）。结果139例患者染色体核型异常,其中119例为性染色体数目异常,20例为性染色体结构异常。另有17例患者为睾丸女性化综合征。1例46,XX男性性反转综合征,1例,46．XY女性性反转综合征及正常男性对照均检测出SRY基因,结论：性染色体异常是导致性发育异常的重要原因。SRY基因的分析为研究性分化原理及性反转综合征的发病机制提供了有价值的资料。     

性发育异常患者的分子遗传学研究

目的　对 9例性发育异常患者进行分子遗传学检查分析以探讨性别异常的原因。方法　聚合酶链反应法(PCR)检测Y染色体长臂重复序列 (Y3、Y4)和SRY基因。结果　Y染色体长臂重复序列的存在与染色体核型一致 ;而 9例患者中 ,2例 46 ,XX男性患者 ,1例 46 ,XY女性患者 ,2例 46 ,XY男性性征发育不良患者和 1例 45 ,X/ 46 ,XY嵌合体患者SRY基因呈阳性 ,其余 3例SRY基因呈阴性。结论　人类的性别决定是以SRY基因为主导 ,一系列基因参与协调表达的调控串模式 ,SRY基因与性别决定有关 ,Y染色体长臂重复序列的扩增对于确认Y染色体的存在与否有重要意义     

蒙古族牙本质发育不全Ⅱ型一大家系临床分析

目的 探明蒙古族一大家系牙本质发育不全症的临床特点和遗传学基础。方法 采用临床与家系调查相结合的方法对该家系临床特点进行分析。结果 该家系中连续5代都出现该病患者,且患者子女中发病率近1/ 2 ,亦无性别差异。该家系患者的临床特点,牙齿X线片等结果显示,发现与已报道的其他民族牙本质发育不全Ⅱ型家系的特点并不完全一致。结论 该蒙古族牙本质发育不全家系属于Ⅱ型,常染色体显性方式遗传。临床表型存在高度的异质性,是否与生活习惯或基因多态性有关有待进一步研究。     

性发育异常患者的细胞分子遗传学分析

目的: 探讨性发育异常患者的细胞分子遗传学特征。方法: 应用多重连接依赖的探针扩增(MLPA)技术对3例染色体核型为46,XX的男性性反转综合征患者及1例女性假两性畸形患者父母进行SRY、CYP21A2、DSS、DAX1、WNT4、SOX9、NR5A1等性别相关基因的拷贝数筛查,并采用细菌人工染色体(BAC)克隆制备探针,以荧光原位杂交技术(FISH)进行基因定位。结果: 3例男性性反转综合征患者经MLPA基因筛查均发现存在单拷贝SRY基因,FISH技术鉴定存在2条X染色体,SRY基因易位于其中1条X染色体的短臂上;女性假两性畸形患者的母亲染色体核型为46,XX,MLPA基因筛查发现其CYP21A2-ex03杂合性缺失,CYP21A1P-ex02杂合性重复;父亲染色体核型为46,XY,MLPA基因筛查发现CYP21A2-ex01和CYP21A2-ex03杂合性缺失,CYP21A1P-ex02和CYP21A1-ex10杂合性重复。结论: 性别决定是以SRY基因为主导、其它多个基因参与的过程,对性发育异常患者进行MLPA基因筛查有利于明确病因。     

性发育异常的病因及遗传学研究

性发育异常为一症候群，其病因不同，临床表现、治疗方法及遗传咨询原则均不同。我们总结十几年发现的１５０例性发育异常患者，进行了病因学构成及遗传学探讨，现将结果报告如下。资料与方法１９８４年－１９９６年１２月本院遗传门诊、妇科门诊及泌尿科门诊疑为性发育异...     

性发育异常患者的细胞遗传学分析

性染色体异常是导致性腺发育不良和生殖器官先天性发育畸形的重要原因之一。本文对遗传咨询门诊中 6 5例因不育、无精症、原发性闭经和外生殖器发育畸形等原因就诊的患者进行染色体检查及临床分析 ,发现性染色体异常 2 5例 ,探讨了性发育异常患者的遗传学基础。对象与方法1 对象 :6 5例患者来自我院遗传咨询门诊 ,主要表现为无精症、原发性闭经、不育和外生殖器发育畸形等。2 方法 :细胞遗传学检查外周血淋巴细胞培养 ,Ｇ显带 ,每例计数 30个中期分裂相 ,分析 3- 5核型 ,必要时加大分析量至 10 0个分裂相 ,以确定嵌合体的比例。结　　果6 5…     

一个遗传性牙本质发育不全家系的分子遗传研究

目的 研究一个常染色体显性牙本质发育不全家系发病的遗传基础.方法 通过对一个DSPP家系临床检查和家族史调查,连锁分析和DSPP基因的突变检测,以及限制性片段长度多态分析方法,分析该家系发病的分子基础.结果 连锁分析发现,该疾病致病基因与微卫星标记D4S1534完全连锁,对位于该区域的DSPP基因进行测序分析,发现一个新的致病突变(c.49C→T,p.Pro17Ser),该突变位于DSPP基因的第1外显子.该家系所有患者中都检测到了这一致病突变,但家系中的正常个体和100个无亲缘关系的正常人中未发现这个突变.结论 p.Pro17Ser是牙本质发育不全Ⅱ型致病基因DSPP的一个新的致病突变.我们的研究进一步拓展了对牙本质发育不全疾病分子遗传基础的认识.     

牙本质发育不全Ⅱ型的家系调查与分析

在口腔医学临床上牙本质发育不全发现较早,早在上世纪30年代就被认识。但作为遗传性疾病其发病率低,尚不能治愈,所以相应的报道并不多见。直到2001年,我国成功克隆了牙本质发育不全Ⅱ型（dentinogenesis imperfectatypeⅡ,DGI—Ⅱ）的致病基因并发现了导致DGI—Ⅱ的基因突变,更多的人开始在基因水平及临床上关注牙本质发育不全这一遗传性疾病。本文报告一例牙本质发育不全Ⅱ型的家系。     

Novel dentin phosphoprotein frameshift mutations in dentinogenesis imperfecta type II

Lee K‐E, Kang H‐Y, Lee S‐K, Yoo S‐H, Lee J‐C, Hwang Y‐H, Nam KH, Kim J‐S, Park J‐C, Kim J‐W. Novel dentin phosphoprotein frameshift mutations in dentinogenesis imperfecta type II. The dentin sialophosphoprotein (DSPP) gene encodes the most abundant non‐collagenous protein in tooth dentin and DSPP protein is cleaved into several segments including the highly phosphorylated dentin phosphoprotein (DPP). Mutations in the DSPP gene have been solely related to non‐syndromic form of hereditary dentin defects. We recruited three Korean families with dentinogenesis imperfecta (DGI) type II and sequenced the exons and exon–intron boundaries of the DSPP gene based on the candidate gene approach. Direct sequencing of PCR products and allele‐specific cloning of the highly repetitive exon 5 revealed novel single base pair (bp) deletional mutations (c.2688delT and c.3560delG) introducing hydrophobic amino acids in the hydrophilic repeat domain of the DPP coding region. All affected members of the three families showed exceptionally rapid pulp chambers obliteration, even before tooth eruption. Individuals with the c.3560delG mutation showed only mild, yellowish tooth discoloration, in contrast to the affected individuals from two families with c.2688delT mutation. We believe that these results will help us to understand the molecular pathogenesis of DGI type II as well as the normal process of dentin biomineralization.     

Analysis of DSPP gene mutation in a Chinese pedigree affected with hereditary dentinogenesis imperfectaCSCD

Objective: To analyze the clinical phenotype of a Chinese pedigree affected with hereditary dentinogenesis imperfecta and mutation of dentin sialophosphoprotein (DSPP) gene. Methods: Affected members underwent intraoral photography, dental film and panoramic radiography. Genomic DNA was extracted from peripheral venous blood samples. Coding regions of the DSPP gene were subjected to PCR amplification and Sanger sequencing. Functional effect of the mutation was predicted with SIFT and PolyPhen-2. The tertiary structure of wild type and mutant proteins were predicted by Swiss-Port. Results: A heterozygous c. 50C>T (p. P17L) mutation was identified in exon 2 of the DSPP gene in the proband and her father. The same mutation was not found among 200 unrelated healthy controls. The Pro-17 residues and its surrounding positions in DSPP are highly conserved across various species. The mutation was predicted to be damaging to the structure of DSPP protein. Conclusion: The c. 50C>T (p. P17L) mutation of the DSPP gene probably underlies the disease in this pedigree. Above finding has expanded the spectrum of DSPP gene mutations and provided a basis for genetic counseling and prenatal diagnosis for this family. © 2018 MeDitorial Ltd. All rights reserved.     

Isolated dentinogenesis imperfecta and dentin dysplasia: revision of the classification

Dentinogenesis imperfecta is an autosomal dominant disease characterized by severe hypomineralization of dentin and altered dentin structure. Dentin extra cellular matrix is composed of 90% of collagen type I and 10% of non-collagenous proteins among which dentin sialoprotein (DSP), dentin glycoprotein (DGP) and dentin phosphoprotein (DPP) are crucial in dentinogenesis. These proteins are encoded by a single gene: dentin sialophosphoprotein (DSPP) and undergo several post-translational modifications such as glycosylation and phosphorylation to contribute and to control mineralization. Human mutations of this DSPP gene are responsible for three isolated dentinal diseases classified by Shield in 1973: type II and III dentinogenesis imperfecta and type II dentin dysplasia. Shield classification was based on clinical phenotypes observed in patient. Genetics results show now that these three diseases are a severity variation of the same pathology. So this review aims to revise and to propose a new classification of the isolated forms of DI to simplify diagnosis for practitioners.     

Bone dysplasia in a child born to parents with osteogenesis imperfecta and pseudoachondroplasia

We report on a boy born to a mother with pseudoachondroplasia and a father with osteogenesis imperfecta (Sillence type III). At birth, the boy was found to have osteogenesis imperfecta type III. Although clinical findings of pseudoachondroplasia were not manifested at the age of 8 months, roentgenographic findings showed characteristics of pseudoachondroplasia in addition to those of osteogenesis imperfecta. He died of respiratory distress at age 15 months. © 1994 Wiley-Liss, Inc.     

常染色体隐性遗传性成骨不全症的分子遗传学研究进展

成骨不全症(osteogenesis imperfecta,OI)又称脆骨症,由于遗传缺陷而引起Ⅰ型胶原结构或功能异常,表现为全身骨骼等结缔组织异常.临床特点是多发性骨折,同时可伴有巨头畸形、蓝巩膜、耳聋、牙齿改变和脊柱后侧凸等.成骨不全症不仪临床表型变异度大,而且遗传异质性高,以常染色体显件或隐性遗传方式传递,本文就常染色体隐性遗传性成骨不全症的分子遗传学研究进展加以综述.     

Effect of paternal age in achondroplasia,thanatophoric dysplasia,and osteogenesis imperfecta

The paternal ages of nonfamilial cases of achondroplasia (AC) (n = 78), thanatophoric dysplasia (TD) (n = 64), and osteogenesis imperfecta (OI) (n = 106), were compared with those of matched controls, from an Italian Indagine Policentrica Italiana sulle Malformazioni Congenite and a South American Estudio Colaborativo Latinoamericano de Malformaciones Congénitas series. The degree of paternal age effect on the origin of these dominant mutations differed among the three conditions. Mean paternal age was highly elevated in AC, 36.30 ± 6.74 years in the IPIMC, and 37.19 ± 10.53 years in the ECLAMC; less consistently elevated in TD, 33.60 ± 7.08 years in the IPIMC, and 36.41 ± 9.38 years in the ECLAMC; and only slightly elevated in OI in the ECLAMC, 31.15 ± 9.25 years, but not in the IPIMC, 32.26 ± 6.07 years. Increased maternal age or birth order in these conditions disappeared when corrected for paternal age. Approximately 50% of AC and TD cases, and only 30% of OI cases, were born to fathers above age 35 years. For AC and TD, the increase in relative incidence with paternal age fitted an exponential curve. The variability of paternal age effect in these new mutations could be due, among other reasons, to the high proportion of germ-line mosaicism in OI parents, or to the localization of the AC gene, mapped to the 4p16.3 region, in the neighborhood of an unstable DNA area. © 1995 Wiley-Liss, Inc.     

A new form of skeletal dysplasia with amelogenesis imperfecta and platyspondyly

We report two patients, born of consanguineous parents, affected by a disorder resulting in mild growth retardation. Hallmarks are amelogenesis imperfecta (absence of the enamel cap) associated with brachyolmia-like anomalies: platyspondyly with short pedicles, narrow intervertebral and interpedicular distances, rectangular-shaped vertebrae with posterior scalloping and herniation of the nuclei, and broad femoral necks. Inheritance appears to be autosomal recessive.     

Root dentin anomaly and a PLG mutation

We report a Thai girl affected with plasminogen deficiency, Type I. Ligneous conjunctivitis was first observed when she was one-month-old. The newly recognized findings include tapered incisor roots as a result of thin root dentin, generalized short tooth roots, and mandibular prognathism. Mutation analysis of PLG demonstrated homozygous c.1193G>A missense mutation. The parents were heterozygous for c.1193G>A mutation. The c.1193G>A mutation is novel and predicted to cause amino acid substitution p.Cys398Tyr. Thin root dentin in the patient who was affected with PLG mutation and immunolocalization of Plg during early root development in mice imply the role of plasminogen in root dentin formation.