表皮松解掌跖角化症一家系KRT9基因突变的分子遗传学研究

发布时间：2018-04-02 02:03

本文选题：掌跖角质化　切入点：表皮松解掌跖角质化　出处：《暨南大学》2010年硕士论文

【摘要】： 研究背景表皮松解性掌跖角化症(epidermolytic palmoplantar keratoderma, EPPK)为常染色体显性遗传性皮肤病,其临床特征表现为掌跖角质层过度增厚。组织学特点为角质形成细胞空泡变性,大量裂解。该病有并发乳腺癌或卵巢癌的风险。EPPK主要由位于17q12-q21上的KRT9基因突变所致。KRT9基因的缺陷破坏了中间纤维的形成,导致细胞的结构及功能发生改变。在已经报道的EPPK家系中,KRT9基因的第1外显子是突变发生的热区。目的通过对一EPPK家系病例进行分子遗传学研究,探讨EPPK的发病机制。通过检索人类中间纤维突变数据库,分析国内外报道的EPPK家系,进一步探讨EPPK的分子遗传学机制及基因型与表型的关系。材料与方法收集1例来自广东梅州的EPPK家系,其中患者11人,共累及5代人。选择20名无亲缘关系的正常人作为对照。应用聚合酶链式反应(PCR)及DNA测序的方法对该家系中7名患者和4名正常成员的KRT9基因进行检测。结果 1.表皮松解掌跖角化症存在遗传异质性,即使同一个家系,家系成员掌跖角质化的程度却有所不同, 2.应用PCR及DNA测序分析方法,确诊到中国人群中的7例掌跖角化症。该家系中7例患者的KRT9基因第1外显子中的第156位密码子发生ATG→ACG的突变,导致甲硫氨酸(Met)被苏氨酸(Thr)取代。 3.在非编码区检测到KRT9基因-99位点存在多态性(G／A)。 4.由于报道的病例数不多,尚不能明确表型与基因型的关系。结论 1.本研究中的7名家系患者均在基因水平上诊断为EPPK患者,主要病因为：KRT9基因第1外显子的第156位密码子发生错义突变,导致甲硫氨酸被苏氨酸取代。 2.本研究再次证实中国人群KRT9基因突变与其他已研究的家系相似,突变位点位于热区。 3.推测KRT9突变导致角蛋白二级结构的改变：错义突变虽然没有改变编码肽链的长度,却改变氨基酸的理化性质,导致螺旋构象的高度破坏,角蛋白亚单位构建异常,最终导致EPPK的临床表现。 4.可优先对热区exon1进行测序来提高工作效率。如果根据临床表型诊断和病理切片初步诊断为EPPK,但对KRT9的1～7外显子测序又未检出突变,为避免漏诊,需要考虑少数病例中KRT1、KRT10和KRT16突变也可以导致EEPK。
[Abstract]:Research background. Epidermolytic palmoplantar keratoderma (EPPKK) is an autosomal dominant hereditary dermatosis, which is characterized by excessive thickening of palmar metatarsal keratinocytes and histopathological features of vacuolar degeneration of keratinocytes. Mass cleavage. The disease has a risk of developing breast or ovarian cancer. EPPK is mainly caused by a defect in the .KRT9 gene in the KRT9 gene located on 17q12-q21, which destroys the formation of intermediate fibers. The first exon of KRT9 gene is the hot region of mutation in EPPK pedigree. Purpose. By studying the molecular genetics of a EPPK family case, the pathogenesis of EPPK was studied, and the EPPK pedigree reported at home and abroad was analyzed by searching the human intermediate fiber mutation database. To further explore the molecular genetic mechanism of EPPK and the relationship between genotype and phenotype. Materials and methods. A case of EPPK family from Meizhou, Guangdong Province was collected. The KRT9 gene of 7 patients and 4 normal members were detected by polymerase chain reaction (PCR) and DNA sequencing. Results. 1. There is genetic heterogeneity in epidermolysis palmoplantar keratosis. Even in the same family, the degree of palmoplantar keratosis in family members is different. 2. Using PCR and DNA sequencing analysis, 7 cases of palmoplantar keratosis were diagnosed in Chinese population. ATG was found in codon 1 of KRT9 gene in 7 patients in this pedigree. 鈫扵he mutation of ACG causes methionine to be replaced by threonine. 3. KRT9 gene-99 locus was found to be polymorphic in non-coding region. 4. Due to the small number of reported cases, the relationship between phenotype and genotype is not clear. Conclusion. 1. In this study, 7 families were all diagnosed as EPPK patients at the gene level. The main cause was a missense mutation at codon 156 of the first exon of the gene, which led to the replacement of methionine with threonine. 2. This study confirmed that the mutation of KRT9 gene in Chinese population was similar to that in other families, and the mutation locus was located in the hot region. 3. It is speculated that KRT9 mutation leads to the change of the secondary structure of keratin: although the missense mutation does not change the length of the encoded peptide chain, it changes the physicochemical properties of amino acids, resulting in the high destruction of helical conformation, and the abnormal construction of keratin subunits. Finally, the clinical manifestation of EPPK is caused. 4. The hot region exon1 sequencing can be given priority to improve the working efficiency. If EPPKs are initially diagnosed according to clinical phenotype diagnosis and pathological section, but no mutation is detected in KRT9 exon 1 / 7 sequencing, in order to avoid misdiagnosis, It is necessary to consider that KRT1 KRT10 and KRT16 mutations may also lead to EEPK in a few cases.
【学位授予单位】：暨南大学
【学位级别】：硕士
【学位授予年份】：2010
【分类号】：R758.5

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