迟发型先天性厚甲家系角蛋白17基因新突变位点的检测

A novel keratin 17 gene mutation in a Chinese pedigree of delayed-onset pachyonychia congenita type II

目的 探讨一迟发型先天性厚甲家系角蛋白 17基因突变和临床表现的关系 ,为先天性厚甲的基因诊断和基因治疗奠定基础。方法 用巢式PCR扩增了迟发型先天性厚甲家系中 9例患者、1名正常人及与该家系无关的 5 0名正常人外周血基因组DNA角蛋白 17基因第 1外显子热点突变区 ,对PCR产物进行DNA序列分析。结果 迟发型先天性厚甲家患者的角蛋白 17基因第 10 9位密码子由AAC突变为GAC ,结果导致天冬酰胺由天冬氨酸替代 (即N10 9D)。而该家系中的正常人及与该家系无关的 5 0名正常人的DNA测序结果均未发现此突变。结论 该家系存在角蛋白 17N10 9D突变 ,为一新的错义突变。角蛋白 171A区后半部的突变可表现为迟发型先天性厚甲II型。

Objective To detect the keratin 17 gene mutation in a Chinese pedigree of typical delayed-onset pachyonychia congenita type II (PC-II) and to explore the relationship between the genetic mutation and the phenotype of PC- II. Methods The DNA was extracted from the blood samples of 19 patients with PC-II in four generations in the pedigree, 1 unaffected member of the pedigree, and 50 un-related normal persons. Nested PCR was used to amplify the mutation hot spot in the exon 1 of keratin 17 gene. The PCR products were directly sequenced to detect the mutation. Results Sequencing of the PCR products revealed that the codon 109 (AAC) was mutated as GAC in the nine affected members of the pedigree, causing the substitution of asparagine by aspartic acid in codon 109 (N109D) located in the 1A domain of keratin 17 gene. No such mutation was found in the unaffected member of the pedigree and the 50 unrelated controls. Conclusion The novel missense mutation (N109D) located in the second half of 1A domain of keratin 17 gene underlies the affected members′ phenotype, delayed-onset pachyonychia congenita type Ⅱ.