背景:I型和II型遗传性血管性水肿(HAE)的发病机制与SERPING1基因编码的缺陷性C1酯酶抑制剂(C1-INH)有关。HAE患者的临床表现存在与C1-INH的血清水平不直接相关的实质性变化。SERPING1变体对C1-INH表达的影响,结构和功能尚未完全理解。
目的:我们研究了SERPING1变异体对C1-INH表达的影响,来自14个没有遗传诊断的家庭的20例HAE患者的结构和功能。
方法:患者接受全外显子组测序(WES)。如果没有发现变异,进行全基因组测序(WGS).除了移码和大量删除,每个C1-INH变体是重组产生的,如果合成和分泌,受到结构性的影响,寡糖和功能分析。
结果:我们鉴定了SERPING1基因中的11个杂合变体,其中5个被分类为致病性(E85Dfs*63,N166Qfs*91,K201Qfs*56,P399A和R466H)和6个具有不确定意义的变体(C130W,I224S,N272del,K273del,L349F和F471C)。通过WGS发现了三个大的杂合缺失。我们的数据表明C130W,N272del,P399A和F471C合成不佳,I224S阻止了C1-INH的适当折叠,而K273del通过添加额外的寡糖损害C1-INH的功能。进一步的评估表明,化合物变体P399A/L349F有助于更严重的临床表型。
结论:我们的WES和WGS的联合方法揭示了每位患者的SERPING1基因变异。重组蛋白生产,然后是系统抗原,结构和功能评估有助于确定HAE的潜在致病机制。
The pathogenesis of hereditary angioedema (HAE) type I and type II is linked to defective C1 esterase inhibitor (C1-INH) encoded by the SERPING1 gene. There are substantial variabilities in the clinical presentations of patients with HAE that are not directly correlated to the serum levels of C1-INH. The impact of SERPING1 variants on C1-INH expression, structure, and function is incompletely understood.
To investigate the influence of SERPING1 variants on the C1-INH expression, structure, and function of 20 patients with HAE from 14 families with no prior genetic diagnosis.
Patients underwent whole-exome sequencing (WES). If no variants were identified, whole-genome sequencing (WGS) was performed. Except for the frameshift and large deletions, each C1-INH variant was recombinantly produced and, if synthesized and secreted, was subjected to structural, oligosaccharide, and functional analyses.
We identified 11 heterozygous variants in the SERPING1 gene, of which 5 were classified as pathogenic (E85Dfs∗63, N166Qfs∗91, K201Qfs∗56, P399A, and R466H) and 6 as variants of uncertain significance (C130W, I224S, N272del, K273del, L349F, and F471C). Three large heterozygous deletions were discovered through WGS. Our data indicate that C130W, N272del, P399A, and F471C are poorly synthesized, I224S prevents proper C1-INH folding, and K273del impairs C1-INH function by adding an additional oligosaccharide. Further evaluation suggests that compound variant P399A/L349F contributes to a more severe clinical phenotype.
Our combined approach of WES and WGS uncovered SERPING1 gene alternations in each patient. The recombinant protein production followed by systematic antigenic, structural, and functional assessment facilitates the identification of underlying pathogenic mechanisms in HAE.