Whole Exome Sequencing And Clinical Characteristics Analysis Of 116 Sporadic Sarcoidosis Patients And 1 Familial Sarcoidosis Family

Background:Sarcoidosis is a multisystem involved disease which caused by unknown etiology and characterized by inflammatory activity accompany with non-caseating granulomatous in affected organs,and lungs were affected mostly.Family aggregation often occurs,and the heritability is estimated to be as high as 66%.The incidence of sarcoidosis varies between different races.The Whole-exome sequencing(WES)for sarcoidosis patients can proposed the candidate mutation sites and genes.And function prediction of the mutations could generate pathogenic mechanism of sarcoidosis which could be further studied and discussed in the future.Objective:To detect the mutation site and genes of patients with familial sarcoidosis,we analyzed the WES results and proposed the candidate genes and mutations of familial sarcoidosis patients.Moreover,we analyzed the underlying pathogenic mechanism of sarcoidosis.We also analyzed the commonness and characteristics of the mutations and genes between 116 cases of sporadic sarcoidosis and 1 familial sarcoidosis family.Besides,we also compared the clinical characteristics of sporadic sarcoidosis patients and analyzed the underlying pathogenic mechanism.Methods:The study included 1 Chinese familial sarcoidosis family who visited our hospital in November 2016,including 3 sarcoidosis patients and 1 healthy family member.And we also included 116 sporadic sarcoidosis patients who visited our hospital from January 1,2016 to December 30,2018.We completed the collection of clinical data of patients.Through database screening and clinical feature association analysis,candidate gene sets of sarcoidosis pathogenic genes were obtained.By comparing the candidate gene sets between sporadic sarcoidosis and familial sarcoidosis patients,and completing the functional analysis of the mutant gene,we screened the candidate genes and completed the functional prediction of the mutant genes and sites.Then,we concluded the related molecular pathway and potential sarcoidosis Pathogenic mechanism.Results:1.This study included a case of sarcoidosis in November 2016,which is a family of pulmonary sarcoidosis of the Han nationality in northern China.The family includes 3 consecutive patients and 1 healthy member,including 2 males and 2 females.The age of onset is 23-69 years,and the proband is Ⅱ-6.WES was performed on patients with familial sarcoidosis and healthy member in sarcoidosis family to screen for unique and rare mutation sites and candidate gene sets of familial sarcoidosis family.Through ExAC,CADD,Polyphen2 and Metascape database analysis,it was found that 27 genes in the database indicate high pathogenicity,of which ZC3H12A,BCR,C5AR2 and INHBB genes in the Metascape database are annotated as "negative regulation of cell secretion".Sanger sequencing confirmed that the mutation in the C.1361 A>G site of ZC3H12A occurred in all 3 patients,but no mutation in healthy member.ZC3H12A gene can negatively regulate Th17 cell differentiation,and may participate in the immune process of sarcoidosis.2.This study also included 116 patients with sporadic sarcoidosis,including 39 males and 77 females,with a male to female ratio of about 1:2,with a median age of 49(29-72)years of diagnosis.The complete WES results of 116 patients with sporadic sarcoidosis and 208 healthy people completed Fisher’s exact test.The results showed that there were 1131 significant mutation sites on 439 genes.3.Family and sporadic sarcoidosis have common candidate genes,including:MUC16,MUC6,PSG11,SLC9B1,TAS2R43,where the SLC9B1 gene coincides with two sites,including chr4:103826757 and chr4:103826769.Genes with nonsynonymous mutations and stop-gain mutations include MUC16,SLC9B1 and TAS2R43.Among them,MUC16 non-synonymous mutations of 116 cases of sporadic sarcoidosis can cause protein hydrophobicity changes,which in turn affect downstream molecular pathways,and proposed as a potential sarcoidosis gene.Conclusion:The genetic mutation could generate the change of immune response in familial pulmonary sarcoidosis patient which is a pathogenic mechanism of the disease.Through WES and gene function analysis,we found that comparing to the healthy member,all of the sarcoidosis patients in this family(Ⅱ-2,Ⅱ-6 and Ⅲ-1)contain the same mutation on ZC3H12A gene,which probably participate in the process of differentiation of Th17 cells.The candidate gene sets of 116 sporadic sarcoidosis patients include MUC16,MUC6,PSG11,SLC9B1,TAS2R43,all involved in innate immune response and adaptive immune response.Among them,MUC16 is related to the chronic progression of sarcoidosis.Moreover,previous studies have found that patients with sarcoidosis may have elevated serum level of MUC16,but the specific mechanism remains to be further studied.