遗传性凝血因子Ⅺ缺陷症两家系基因分析

Genetic analysis of two lineages of hereditary coagulation factor Ⅺ defects

目的:对两个遗传性凝血因子Ⅺ缺陷症家系共8个成员F11基因进行分析,为评估突变基因的致病性和出血风险提供参考。方法:收集先证者及其家系成员的临床资料,检测家系成员的凝血功能、凝血因子Ⅺ活性(FⅪ:C),并对出血情况进行评分等。提取家系成员的DNA,对其F11基因第1~15外显子及其侧翼序列进行PCR扩增、纯化和测序比对,确定F11基因型,并对F11基因进行分析。若发现错义突变,则建立突变蛋白的晶体结构模型检测突变可能产生的结构效应。结果:两个家系所有成员的FⅪ:C呈不同程度下降,出血评分不同。家系A先证者APTT 125.7s,基因型为F11 Tyr369Ter纯合突变,其余家系A成员均为F11 Tyr369Ter杂合突变。家系B先证者及其妹妹APTT分别为100.2s、128.10s,基因型均为F11 Leu172Pro/Gln263Ter复合杂合突变,父母基因型分别为F11 Gln263Ter、F11 Leu172Pro杂合突变。其中F11 Leu172Pro突变为错义突变,在FⅪ解析晶体结构建立的模型中可见Leu172Pro突变未导致结构上的明显变化。结论:3种F11基因突变Tyr369Ter、Gln263Ter、Leu172Pro是导致FⅪ缺陷症的分子发病机制之一,出血症状不等,其中F11 Tyr369Ter纯合突变临床病例既往未曾报道。

Objective: We conducted genotype analysis on a total of 8 members of two distinct families with hereditary coagulation factor Ⅺ deficiency, aiming to help in assessing the pathogenicity and bleeding risk of specific genotypes. Methods: The clinical data of 2 probands and their family members were collected. The coagulation function, coagulation factor Ⅺ activity(FⅪ:C) and the bleeding score and other indicators were tested. To determine the FⅪ genotype, DNA of the 8 family members was extracted, followed by sequencing of all exons and the flanking sequence of the F11 gene. Finally, F11 genotype was determined and the F11 gene was analyzed.If missense mutations were found, the crystal structure model of the mutant protein was established to detect the possible structural effects of the mutation. Results: The FⅪ: C of all the members of the two families were decreased to different degrees, and the bleeding scores were different. The proband from family A, APTT of 125.7 s,with homozygous mutation of F11 Tyr369 Ter, whereas the rest of the family members were heterozygous for the same mutation. The probands and her sister from family B, APTT of 100.2 s and 128.10 s, with shared a compound heterozygous mutation of F11 Leu172 Pro/Tyr369 Ter, and the parental genotypes were F11 Gln263 Ter and F11 Leu172 Pro heterozygous mutations. Among them, the mutation of F11 Leu172 Pro was a missense mutation,and it could be seen that the mutation of Leu172 Pro did not lead to significant structural changes in the model established by FXI analytic crystal structure. Conclusion: The three of F11 gene mutations, Tyr369 Ter, Gln263 Ter and Leu172 Pro, are one of the molecular pathogenesis of FXI deficiency, with different bleeding symptoms, and the clinical case of homozygous mutations of F11 Tyr369 Ter has not been reported before.