KRT14基因新突变导致的单纯型大疱性表皮松解症家系的研究

Study of a family with epidermolysis builosa simplex resulting from a novel mutation of KRT14 gene

目的探讨一个包含4代9例患者的单纯型大疱性表皮松解症家系的遗传学病因以及表型特点。方法应用高通量目标区域捕获测序分析先证者大疱性表皮松解症的相关基因。在发现疑似突变后，用Sanger测序对其家系进行分析，同时应用Mutationtaster、Poly Phen-2、Provean、SIFT等软件以及NCBI网站对突变位点的致病性和保守性进行预测，并用100名正常人作为对照。结果先证者KRTj4基因存在一个新的C．1234A〉G（P．Ile412Val）杂合突变。家系分析提示所有患者均携带同样的突变。值得注意的是，3名成员（包括2例患者和1名正常个体）的KRT14基因存在一个人类基因突变数据库收录的c．1237G〉A（P．Ala413 Thr）杂合突变，而在其余7例患者中未发现该突变，提示C．1237G〉A（P．Ala413Thr）并非致病突变。在100名正常对照中均未检测到上述两种突变。NCBI保守性分析提示，两个位点均高度保守，而c．1234A〉G（P．11e412Val）为强致病性，c．1237G〉A（P．Ala413Thr）则可能为多态。结论KRT14基因c．1234A〉G（P．Ile412Val）杂合突变很可能是该家系的遗传学病因。C．1237G〉A（P．Ala413Thr）氨基酸改变可能是一种多态。对于有多个致病基因的遗传病，高通量目标区域捕获测序比传统的Sanger测序更高效、准确、省时和低廉，更适合用于临床检测。

Objective To determine the molecular etiology for a Chinese pedigree affected with epidermolysis bullosa simplex （EBS）. Methods Target region sequencing using a hereditary epidermolysis bullosa capture array combined with Sanger sequencing and bioinformatics analysis were used. Mutation taster, PolyPhen-2, Provean, and SIFT software and NCBI online were employed to assess the pathogenicity and conservation of detected mutations. 100 healthy unrelated individuals were used as controls. Results Target region sequencing showed that the proband has carried a unreported heterozygous c. 1234A〉G （p. Ile412Val） mutation of the KRT14 gene, which was confirmed by Sanger sequencing in other 8 affected individuals hut not among healthy members of the pedigree. Bioinformatics analysis indicated that the mutation is highly pathogenic. Remarkably, 3 members of the family （2 affected and 1 unaffected） have carried a heterozygous c. 1237G〉A （p. Ala413Thr） mutation of the KRT14 gene, which was collected in Human Gene Mutation Database （HGMD）. Bioinformatics analysis indicated that the mutation may not be pathogenic. Both mutations were not detected among the 100 healthy controls. Conclusion The novel c. 1234A〉G （p. Ile412VaD mutation of the KRT14 gene is probably responsible for the disease, while c. 1237G〉 A （p. Ala413Thr） mutation of KRT14 gene may be a polymorphism. Compared with Sanger sequencing, target region capture sequencing is more efficient and can significantly reduce the cost of genetic testing for EBS.