Clinical Heterogeneity And Influencing Factors Of Hereditary Angioedema In Chinese Patient

Objectives:Hereditary angioedema(HAE)is a rare and life-threatening autosomal dominant genetic disease characterized by recurrent and unpredictable skin and mucosal swelling.H AE has obvious clinical heterogeneity,including the time,location,and severity of edema attacks vary greatly from patient to patient,and even the symptoms of each attack vary greatly in the same patient,which makes the diagnosis of the disease a great challenge.Therefore,characterizing the clinical heterogeneity of HAE patients in China can help clinicians better understand the characteristics of the disease and facilitate the early diagnosis of HAE patients.In addition,HAE also has significant genetic heterogeneity.More than 900 variants in the SERPING1 gene associated with HAE have been identified.However,only about 50 variants have been identified in Chinese HAE patients.Therefore,identifying new SERPING1 gene variants and updating the gene mutation profile of HAE patients in China are essential to facilitate molecular diagnosis and genetic counseling of HAE.Methods:Ninety-seven unrelated patients with HAE diagnosed in the Department of Allergy at Peking Union Medical College Hospital from 2013 to 2022 were included.The clinical characteristics of patients were collected by questionnaire,including demographic information,age of onset,phenotype,family history,medications,and laboratory tests.A retrospective analysis was performed to clarify the clinical characteristics of HAE patients in China.To explore the genetic heterogeneity of HAE patients,peripheral blood was collected from patients and variants were detected by Sanger sequencing and Multiplex Ligation dependent Probe Amplification(MLPA).Variants were searched in public databases to clarify whether the variant had not been reported before.The public databases used included The Human Gene Mutation Database(HGMD?)and the Leiden Open Variation Database(LOVD).The American College of Medical Genetics and Genomics/Association for Molecular Pathology(ACMG/AMP)guidelines were used to determine the pathogenicity of variants.Results:Of the HAE 97 patients,96.9%,69.1%and 66.0%reported previous skin edema,gastrointestinal edema and laryngeal edema,respectively.Ninety patients carried 76 different variants.Seven patients were not detected with pathogenic variants.Of the 76 variants,35 were reported for the first time and have been submitted to the public database ClinVar.Missense and in-frame variants were the most common variants(36.8%),followed by frameshift(28.9%),nonsense(14.5%),splice site(13.2%)variants,and gross deletions/duplications(6.6%).Conclusions:This part of the study updates the clinical characteristics and gene mutation profile of HAE patients in China,which helps clinicians to understand the disease characteristics of HAE more comprehensively and provides more evidence for accurate diagnosis of HAE and genetic counseling.Objectives:Hereditary angioedema(HAE)is an autosomal dominant disorder characterized by edema of the skin and submucosal tissues.The clinical heterogeneity of HAE,as evidenced by differences in the age of onset,frequency of attacks,precipitating factors,prodromal signs,severity of edema,and site of edema,is one of the major causes of misdiagnosis and misdiagnosis of HAE in China.The mechanisms of clinical heterogeneity in HAE are still unclear,and there is a lack of clinical biomarkers to predict edema phenotype and disease severity.In this study,we aim to investigate the factors affecting the clinical heterogeneity of HAE in a multidimensional manner and to search for biomarkers associated with the phenotype and severity of HAE.Changes in small molecule metabolites are the result of changes in gene and protein function and directly reflect the end state of the biological system.Therefore,the first aim of this study is to reveal the changes in small molecule metabolites in HAE patients and their association with edema phenotype.Furthermore,diseases are influenced by genetic and environmental interactions,and microenvironmental changes often affect the disease state.Therefore,the second aim of this study was to reveal the impact of microbiota alterations on the phenotype and severity of HAE.It is expected that this study will explore more biomarkers associated with clinical heterogeneity of HAE and advance the individualized prevention and treatment of HAE patients.Methods:This study includes two parts:Metabolomics characteristics of HAE patients and throat microbiota characteristics of HAE patients.1.Metabolomic characteristics of HAE patients:We performed a comprehensive metabolic analysis using high-performance liquid chromatography-tandem mass spectrometry(HPLC-MS/MS).In this part of the study,34 patients with HAE and 82 healthy controls(HC)were included.Urine samples from the study subjects were collected for metabolomic assays to map the metabolic profiles of HAE patients.In addition,we compared metabolome differences in HAE patients carrying different mutation types to clarify the effect of genetic heterogeneity on the metabolome.2.Throat microbiota characteristics of HAE patients:36 patients with HAE were included in this part of the study,and a total of 17 unrelated healthy controls were included from the patients’ families.Pharyngeal swab samples were collected from the study subjects and 16S rRNA sequencing was performed.Characteristic flora associated with disease and disease phenotypes were identified by comparing flora differences between healthy controls and patients,and between patient groups with different phenotypes.Characteristic flora associated with disease severity were further identified by correlation analysis.Results:1.Metabolomic characteristics of HAE patients:A total of 795 metabolites were detected and quantified.We set variable importance in projection(VIP)values>1.0,q-values(corrected p-values)<0.05,and fold change(FC)≥1.2 or FC ≤0.8 as thresholds for screening differential metabolites.Based on this threshold,we screened 73 metabolites that were significantly altered in HAE patients.Among them,several metabolites associated with riboflavin metabolism,the citrate cycle,oxidative stress,and inflammation,including xanthine,oxypurinol,vitamin B2,and isocitrate,were significantly altered in HAE patients.We further explored whether metabolite differences existed between HAE patients carrying missense mutations and HAE patients carrying shift mutations.The findings did not reveal significantly altered metabolites in HAE patients carrying different mutation types.2.Throat microbiota characteristics of HAE patients:In each study group,the throat microbiome was mainly occupied by Firmicutes,Bacteroidetes,Proteobacteria,and Fusobacteria.By comparing patients of different subtypes,we found that the species richness and diversity of the pharyngeal microbiota were significantly lower in HAE patients who had recent episodes of laryngeal edema.The relative abundance of Bacteroidetes and Prevotellaceae was significantly increased in patients with recent episodes of laryngeal edema,compared to patients without recent episodes of laryngeal edema.In addition,we found a positive correlation between HAE episode severity scores and the relative abundance of Bacteroidetes.Conclusions:1.Metabolomic characteristics of HAE patients:This part of the study depicts for the first time the metabolic profile of HAE patients.Our findings highlight those metabolic disturbances in the purine metabolism,riboflavin metabolism,and tricarboxylic acid cycle may be associated with HAE.Although their biochemical significance requires further experimental validation,these findings may help to identify potential metabolic biomarkers associated with HAE.2.Throat microbiota characteristics of HAE patients:We report for the first-time alterations in the throat microbiota of HAE patients and explore the correlation between bacteria and edema severity.The findings show that the relative abundance of Bacteroidetes correlate with recent episodes of HAE edema and the severity of the episodes.These findings may help to understand the disease course in HAE patients and to develop new preventive and therapeutic strategies in a timely manner.