一例显性营养不良型大疱性表皮松解症的基因突变检测

目的 研究1例营养不良型大疱性表皮松解症家系中的基因突变情况.方法 经组织病理、电镜及免疫荧光方法结合临床诊断为显性营养不良型大疱性表皮松解症1例,采用聚合酶链反应(PCR)DNA直接测序,限制性内切酶反应及应用D3S1359、D20S161、D5S818、D17S1293、CSFIPO五个座位微卫星DNA多态标志的方法对此例患者家系进行基因突变情况检测.结果 家系中患者存在COL7A1上第6240位鸟嘌呤G被腺嘌呤A替代突变导致Ⅶ胶原第2043位的甘氨酸被精氨酸替代,而其父母及对照的健康人均不存在此突变.结论 G2043R是引起该家系临床病变的特异突变,不是多态性变化,且此突变为一个denovo突变.     

Hallopeau-Siemens型隐性营养不良型大疱性表皮松解症一例的基因突变研究

目的鉴定一常染色体隐性遗传营养不良型大疱性表皮松解症家系的基因突变。方法应用PCR、DNA直接测序明确突变位点,根据突变位点设计特异性引物,用PCR检测突变位点从而进一步确定该家系的致病原因。结果发现该患者COL7A1基因的一条等位基因第2号外显子上存在S48P的错义突变,而另一条等位基因第27号外显子上存在3625del11缺失突变,造成编码区阅读框架的移位,最终导致蛋白终止密码(PTC)的产生。隐性营养不良型大疱性表皮松解症患者这种两个突变的组合在国际上为首次报道。结论 COL7A1基因的缺失突变和错义突变引起该患者临床症状的特异突变。     

COL7A1与PLEC双基因突变致大疱性表皮松解症一例国内首报

【摘要】 目的 对1例营养不良型大疱性表皮松解症患儿家系进行基因突变分析。方法 收集1例营养不良型大疱性表皮松解症患儿临床资料,提取患儿及其父母外周血DNA进行全基因组外显子测序,将测序结果与既往报道的大疱性表皮松解症基因进行比对,比对结果采用Sanger测序方法进行验证并预测生物学信息,在100例健康对照中验证该位点。结果 患儿存在复合杂合突变,共携带3个致病突变,即COL7A1基因c.3625_3635 del11、c.6270delT突变和PLEC基因c.12772G＞A突变。其中COL7A1基因c.6270delT突变和PLEC基因c.12772G＞A突变皆为新发突变。COL7A1基因c.3625_3635 del11及c.6270delT突变来自父亲,导致肽链合成提前终止,产生截短蛋白;PLEC基因c.12772G＞A突变来自母亲,导致网蛋白第4258位谷氨酸被赖氨酸替代（p.Glu4258Lys）。结论 该患儿是由COL7A1与PLEC双基因突变所致的常染色体隐性遗传营养不良型大疱性表皮松解症。     

显性营养不良型大疱性表皮松解症家系中COL7A1基因突变的研究

营养不良型大疱性表皮松解症是一组遗传性皮肤病^[1],是由于编码基底膜下带锚原纤维的主要组成成分Ⅶ型胶原的基因COL7A1发生突变所致^[2]。显性营养不良型大疱性表皮松解症(DDEB)主要是由于COL7A1三螺旋区的甘氨酸替代突变导致。本研究对一个DDEB家系进行了基因突变的研究。     

白色丘疹样营养不良型大疱性表皮松解症1例

白色丘疹样营养不良型大疱性表皮松解症是营养不良型大疱性表皮松解症（epidemlolysis bullosa dystrophica,DEB）的一种类型,可为常染色体显性遗传和隐性遗传,少见散发病例。最近我科诊治1例,现报告如下。     

痒疹样营养不良型大疱性表皮松解症一家系的基因突变

目的 鉴定一痒疹样营养不良型大疱性表皮松解症家系的基因突变,为进一步开展基因诊断和基因治疗奠定基础.方法 应用聚合酶链反应(PCR)、DNA直接测序明确突变位点,根据突变位点设计等位基因特异性引物,用PCR来检测突变位点以及采用逆转录-聚合酶链反应(RT-PCR)和克隆测序进一步确定该家系的致病原因.结果 该家系中患者COL7A1基因的87号外显子存在剪接位点突变,导致87号外显子被剪切,Ⅶ型胶原的胶原区合成后缺少了23个氨基酸.健康对照不存在此突变.结论 COL7A1基因剪接位点的突变是引起该家系临床症状的特异突变,而非多态性改变.     

遗传性营养不良型大疱性表皮松解症1例

大疱性表皮松解症（DEB）是一组遗传性皮肤病，表现为皮肤和黏膜受轻微机械性损伤后或自动形成大疱或血疱。根椐临床、遗传方式及病理组织中大疱的位置，该组皮肤病分为表皮内型（单纯性）、交界性和营养不良性大疱性表皮松解症三类，其中营养不良型又分为显性遗传（RDEB）和隐性遗传（DDEB）两种亚型。我们遇到1例轻型隐性遗传营养不良型大疱性表皮松解症，现报道如下。     

遗传性皮肤病

痒疹型营养不良型大疱性表皮松解症2例；隐性遗传营养不良型大疱性表皮松解症1例;表皮松解性角化过度型鱼鳞病1例;板层状鱼鳞病两家系TGM1基因的突变;厚皮性骨膜增生症二例报道     

Pasini型大疱性表皮松解症1例

Pasini型大疱性表皮松解症（epidcrmolysis bullosa pasini type）又名白色丘疹样营养不良型大疱性表皮松解症（albopapuloid dystrophic epidermolysis bullous）,是显性贵传性营养不良型大疱性表皮松解症（epidermolysis bullosa dystrophica dominant,DDEB）的一种亚型,常为家族成员共同发病。笔者报告1例单发患者。     

胫前显性营养不良型大疱性表皮松解症基因突变研究

目的 探讨Ⅶ型胶原基因（COL7A1）在胫前显性营养不良型大疱性表皮松解症（DDEB-Pt）发病中的意义。 方法 收集中国汉族1例DDEB-Pt散发患者及其家庭成员和100例健康对照的外周血标本,用改良盐析法提取外周静脉血中的基因组DNA,通过PCR反应扩增和测序进行序列分析。 结果 测序结果显示,COL7A1基因73号外显子的第6109位碱基鸟嘌呤（G）转化为腺嘌呤（A）,使得三螺旋区第2037位密码子由GCT变成ACT,编码氨基酸由甘氨酸（Gly）变为精氨酸（Arg）,即c.G6109A（p.Gly2037Arg）甘氨酸替换突变。 结论 COL7A1 基因甘氨酸替换突变为致病性突变,是一新发突变。     

Somatic mosaicism for the COL7A1 mutation p.Gly2034Arg in the unaffected mother of a patient with dystrophic epidermolysis bullosa pruriginosa

Dystrophic epidermolysis bullosa (DEB) is a heritable blistering disorder caused by mutations in the type VII collagen gene, COL7A1. Although revertant mosaicism is well known in DEB, ‘forward’ somatic mosaicism, in which a pathogenic mutation arises on a wild‐type (WT) background, extending beyond the germ cells, has not been reported. It is therefore unknown what proportion of sporadic dominant DEB (DDEB) cases result from de novo mutations or somatic mosaic parents. In the clinically unaffected mother of a patient with DDEB pruriginosa due to the p.Gly2034Arg mutation, we identified the p.Gly2034Arg mutation in a proportion of lymphocytes and skin cells (mutational load 10–25%). Our data emphasize that forward mosaicism occurs in DDEB and highlight that mutation analysis should always be performed in the parents of sporadic DDEB patients to confirm the de novo status of the mutation. Ultimately, this will reveal the frequency of true de novo mutations and somatic mosaicism in parents, which has important implications for genetic counselling. Our data indicate that the threshold of mutant type VII procollagen to develop DDEB must be higher than 10–25%, which provides a rationale for therapeutic approaches aimed at increasing the WT : mutant type VII collagen ratio.     

Clinical Criteria for Differentiating between Recessive and Dominant Forms of Dystrophic Epidermolysis Bullosa,Elaborated from an Analysis of 119 Cases

We attempted to establish clinical criteria which differentiated between recessive dystrophic epidermolysis bullosa (RDEB) and dominant DEB (DDEB), since these two groups show prominent differences in prognosis, genetic recurrence risk and response to some types of treatment. The total of 119 cases examined consisted of our own 9 cases (2 of RDEB and 7 of DDEB) and 110 cases (26 of RDEB and 84 of DDEB) collected from the medical literature. They were analyzed by calculating the sensitivity and specificity of ten clinical features. We concluded that, syndactyly, presence of complications, dental lesions, remission-less course, and oral lesions are strongly indicative of RDEB (more than 70% specific). Intractable skin ulcer is suggestive of RDEB (more than 55% specific). Nail lesions, scar and atrophy, milia and pigmentation are not helpful in the differentiation because of their commonality. The proposed criteria are simple, reliable, and practical, providing us with a useful tool for differentiation of RDEB and DDEB in daily practice.     

The clinical spectrum of dystrophic epidermolysis bullosa

BACKGROUND: Dystrophic epidermolysis bullosa (DEB) is a genodermatosis resulting from mutations in COL7A1, the gene encoding type VII collagen. The site and specific nature of the underlying mutation determine the clinical phenotype, which ranges widely from a severe mutilating condition to a relatively mild disorder. OBJECTIVES: To document the clinical spectrum of DEB within a defined complete population. METHODS: Since 1992, when compilation of the U.K. epidermolysis bullosa register began, an exhaustive search for DEB sufferers within the Scottish population has been undertaken and their clinical features comprehensively recorded. RESULTS: One hundred and twenty-eight DEB sufferers have been identified within the Scottish population. In descending order, the frequencies of the different forms of DEB were dominant DEB (DDEB) in 88 individuals (68%), DEB of uncertain inheritance in 24 (19%) and recessive DEB (RDEB) in 16 patients (13%). Within this latter group, nine (7%) had the mutilating Hallopeau-Siemens subtype (RDEB-HS), five (4%) had localized (RDEB-loc) and two (2%) had a predominantly flexural (inverse) form of RDEB. During the study, two patients with RDEB died from squamous cell carcinomas (SCCs), one originating in the skin and the second arising in the oesophagus. Gastrointestinal problems such as dysphagia, constipation and anal fissures, and restriction of mouth opening were experienced by the majority of patients with RDEB and by a significant minority of DDEB sufferers. Pseudosyndactyly was most severe in RDEB-HS, all those over 9 years of age having mitten deformities of the hands. Milder pseudosyndactyly or flexion contractures of the fingers were present in younger patients with this subtype, in most adults suffering from other subtypes of RDEB and in 6% of those with DDEB. External ear involvement, a feature not often reported in DEB, was common in RDEB and also occurred in a minority of those with DDEB. Pruriginous lesions and albopapuloid lesions were each present in both DDEB and RDEB. CONCLUSIONS: Most patients with DEB have relatively mild dominantly inherited disease, only a minority suffering from severe recessive subtypes. Scarring, gastrointestinal involvement, albopapuloid lesions and a pruriginosa-like pattern each occur in both DDEB and RDEB. With increasing age, SCC is a major cause of morbidity and mortality.     

Dominant dystrophic epidermolysis bullosa caused by a novel G2037R mutation and by a known G2028R mutation in the type VII collagen gene (COL7A1)

An autosomal dystrophic epidermolysis bullosa (DDEB) is a hereditary mechanobullous disease characterized by blistering of the skin and the mucous membrane. DDEB is caused by a heterozygous mutation in the COL7A1 gene encoding type VII collagen, the major component of anchoring fibrils, and phenotypically classified into several types. We experienced two boys with DDEB and examined the mutation analyses of the COL7A1 genes of the two patients and their fathers to clarify the relationship between the genotypes and phenotypes, that is, the mutation sites of COL7A1 gene and the clinical types of DDEB. The case 1 and 2 patients and their fathers revealed a heterozygous nucleotide G to A transition at position 6109 and 6082 in 73 exon of COL7A1, which resulted in a glycine to arginine substitution (G2037R and G2028R), respectively. G2037R found in the case 1 patient was a novel mutation. There was no clear relationship recognized between the two mutation sites in the COL7A1 gene and the clinical variations.     

Exon 87 skipping of the COL7A1 gene in dominant dystrophic epidermolysis bullosa

Dystrophic epidermolysis bullosa (DEB) is a rare, inherited, blistering disorder resulting from mutations in the COL7A1 gene, which encodes the anchoring fibrils, type VII collagen. We herein describe a further Japanese girl diagnosed with dominant DEB (DDEB). She had blisters sporadically and erosions healed with mild scarring and milia on the knees and pretibial regions. Severe pruritus was present at this time. Direct nucleotide sequencing of genomic DNA disclosed a heterozygous same splice-site mutation c.6900G>A in the COL7A1, which causes in-frame exon 87 skipping. So far, five different COL7A1 mutations leading to exon 87 skipping have been identified in rare forms of DEB: four DDEB pruriginosa and one pretibial DDEB. Therefore, a recent study suggested that exon 87 skipping in COL7A1 was related to the phenotype of DDEB pruriginosa. When she was 18 years old, however, the blister formation and pruritus markedly decreased. Therefore, her clinical symptoms were consistent to very mild DDEB but not to DDEB pruriginosa. Taken together, in-frame exon 87 skipping through c.6900G>A mutation may account for the mild skin features, rather than DDEB pruriginosa, in the present case.     

显性营养不良型大疱性表皮松解症家系临床表现与诊断分析

目的　研究显性营养不良型大疱性表皮松解症 (DDEB)家系的临床、遗传特点及其基底膜带 (BMZ)结构缺陷 ,并探讨DDEB亚型的发生机制。方法　采用间接免疫荧光 (IIF)和电镜研究 3位DDEB先证者皮损 ,并对其家系进行实地调查。结果　①符合常染色体显性遗传 ;②各家系平均发病年龄差异较大 ;③同一家系中有不同的DDEB亚型 ;④IIF用鼠抗人单克隆抗体LH7∶2检测Ⅶ型胶原 ,家系 1先证者BMZ处荧光较强 ,与正常对照无明显差异 ,家系 2、3先证者荧光明显弱于对照 ;⑤透射电镜示裂隙位于BMZ致密板下 ,锚原纤维数量减少、排列紊乱。结论　同一DDEB家系中 ,不同患者的表现度不同可能导致不同的DDEB亚型 ,IIF和电镜检测患者皮损有助于诊断。     

Squamous cell carcinoma in a family with dominant dystrophic epidermolysis bullosa: a molecular genetic study

Squamous cell carcinoma in a family with dominant dystrophic epidermolysis bullosa: a molecular genetic study Squamous cell carcinoma (SCC) is a frequent complication in the severe, recessively inherited forms of dystrophic epidermolysis bullosa (RDEB), however, only rarely reported in dominant DEB. Although the SCCs in RDEB are frequently well-differentiated by histopathology, they often have a poor prognosis due to multicentricity, rapid invasiveness, and development of distant metastases. In this study, we sought to determine the molecular basis of DDEB in a family with the unusual occurrence of SCCs. Specifically, a large DDEB family with 2 individuals being affected with SCC was analyzed for potential mutations in the type VII collagen gene (COL7A1) by heteroduplex scanning and direct nucleotide sequencing of PCR amplified segments of the gene. This mutation detection strategy disclosed a G-->A transition at nucleotide position 6,235 which resulted in substitution of a glycine by arginine within the collagenous region of COL7A1. This study establishes, for the first time, the molecular basis in a family with DDEB/SCC. Clinically, this study reemphasizes the importance of vigilance in surveying DEB patients, not only those with recessive but also with dominant inheritance, for SCC.     

Identification of the glycine-to-arginine substitution G2043R in type VII collagen in a family with dominant dystrophic epidermolysis bullosa from Hungary

Abstract Epidermolysis bullosa (EB) represents a group of genodermatoses characterized by fragility and easy blistering of the skin. In the dystrophic forms of EB (DEB), blisters occur below the basement membrane, at the level of the anchoring fibrils. In the dominantly inherited forms (DDEB), the predominant type of mutation detected thus far is the substitution of a glycine residue which occurs within the collagenous domain of the molecule characterized by the repeating Gly-X-Y amino acid sequence. In this study, we searched for mutations in DDEB in a family from Hungary, by PCR amplification of segments of COL7A1, followed by heteroduplex analysis. Examination of the PCR fragment corresponding to exon 73 revealed a heteroduplex in affected individuals from the family. Sequence analysis revealed a G-to-A transition at nucleotide 6127 in the triple-helical domain of COL7A1, which converted a glycine residue at amino acid position 2043 to an arginine. This report represents the second incidence of this mutation. G2043R. described first in a family with DDEB from Italy.     

Diagnostic dilemma of “sporadic” cases of dystrophic epidermolysis bullosa: a new dominant or mitis recessive mutation?

Abstract: Dystrophic forms of epidermolysis bullosa (DEB), characterized by mutations in the type VII collagen gene (COL7A1), are inherited either in an autosomal dominant or autosomal recessive fashion, and sporadic, de novo cases have also been reported. Clinically, the dominant forms (DDEB) can be indistinguishable from the mild, mitis forms of recessively inherited DEB (M-RDEB). This situation poses a dilemma in case of families with 1 mildly affected individual and clinically normal parents: Is it a new dominant or mitis recessive DEB? In this study we review 2 cases with mild DEB, the parents being clinically normal. One of the cases was shown to be a compound heterozygote for 2 silent missense mutations (R2063W/G2366S), thus being diagnosed as M-RDEB. The second case had a single glycine substitution mutation (G2079E) in COL7A1 and had therefore DDEB. These findings have implications for the genetic counseling of these families concerning the risk of recurrence of the disease in subsequent pregnancies in the present and future generations.     

Multiple Milia as an Isolated Skin Manifestation of Dominant Dystrophic Epidermolysis Bullosa: Evidence of Phenotypic Variability

We report a Japanese pedigree with dominant dystrophic epidermolysis bullosa (DDEB) harboring the p.G2251E mutation of COL7A1. The proband of this pedigree presented with multiple milia as an isolated skin manifestation without a history of blistering and subsequently developed generalized intractable blisters, suggesting that multiple milia could be a primary manifestation of DDEB. Her mother exhibited nail dystrophy and pruritic nodules and her elder sister was unaffected, despite having the same COL7A1 mutation. Inter‐ and intrafamilial clinical variability are often observed in DDEB, so we should be aware of this factor to provide appropriate genetic counselling.