| الوصف: |
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 HAE patients 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.We investigated the influence of SERPING1 variants on the C1-INH expression, structure and function of 20 HAE patients 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. |
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