蛋白C基因C5498T致Ⅰ型遗传性蛋白质C缺陷症

目的 对一个遗传性Ⅰ型蛋白C(PC)缺陷症家系进行基因突变的检测。方法 分别用ELISA和发色底物法测定血浆蛋白Ｃ活性和抗原。用PCR法对先证者PC基因的9个外显子及其侧翼、内含子2序列进行扩增,PCR产物纯化后直接测序,检测其基因突变。突变位点经限制性内切酶分析证实。结果先证者的蛋白C活性和抗原分别为26％和1．43g／L。先证者表现为PＣ基因外显子3区杂合错义突变Ｃ5498T,引起Arg15→Ｔrp。在基因启动子区存在2405C／T、2418A／G、2583A／T多态性。结论 该突变导致遗传性Ⅰ型PC缺陷症。

Type I hereditary protein C deficiency due to C5498T mutation in protein C gene

Objective To identify the gene mutation in a Chinese pedigree of type I hereditary protein C deficiency. Methods The plasma levels of protein C activity (PC: A), protein C antigen (PC: Ag), protein S activity, and anti-thrombin activity (AT: A) of the propositus, male, aged 7, and 11 members of the pedigree were detected using ELISA and chromogenic assay respectively. All of the nine exons and intron-exon boundaries of protein C gene of the propositus were analyzed by direct sequencing of the corresponding amplified PCR products in DNA from the propositus. Restriction enzyme site analysis was used to confirm the mutation. Results The plasma concentrations of protein C activity and antigen of the propositus were 26% and 1.43 g/L respectively. The PC:Ag and PC:A of his father were normal. Decreased PC:A level was seen in his mother and 4 of his maternal pedigree. PS:A and AT:A were all normal in all of the pedigree members. A C5498T heterozygous mutation in exon 3, resulting in the substitution of Arg for Trp at the 15th amino acid, was identified in the propositus and 8 of his relatives. This mutation was confirmed by restriction enzyme site analysis. Mutations C/T at position 2405, A/G at position 2418, and A/T at position 2583 in the protein C promoter region were confirmed in the propositus and all members of the pedigree. Conclusion C5498T heterozygous mutation in exon 3 of protein C gene, first reported in China, leads to type I hereditary.