Identification Of Susceptibility Genes Of Two Autoimmune Bullous Skin Disease-pemphigus Vulgaris And Bullous Pemphigoid

Background: Autoimmune Bullous Diseases(AIBDs)is an autoimmune disease clinically characterized by erythema,bullae and erosion.AIBDs affecting the elder typically and the increased incidence of AIBDs were reported worldwide.Autoantibodies target the autoantigen in the surface of keratinocytes or basal membrane band leads to the loss of adhesion junction or acantholysis and finally result in the formation of bullae in the epidermis or subepidermal.According to the location of blisters,it can be divided into epidermal bullous disorders and subepidermal bullous disorder.It's lingering and difficult to cure.AIBDs can affect the physical and mental condition of patients and family members of patients,and cause enormous losses.The etiology and pathogenisis of AIBDs is still unclear,immune factor,environmental factor and genetic factor are thought to play key role in AIBDs.Pemphigus Vulgaris(PV)is the most common type of epidermal bullous disorders which mainly affect skin and mucous membranes with positive Nikolsky sign.Oral mucous membrane is the first involved zone in 60% of PV.PV with characterized of low incidence but Serious consequences.The annual incidence was about 0.76 to 16.1 per million worldwide.The mortality in PV was range from 5% to 30%,two to three times higher than normal.The pathogenesis of PV is not entirely clear,most people think Desmoglein3 play important role in the pathogensis os PV.Desmoglein3 is a kind of Bridging calcium gluconate,working in the adhesion of intercellular and was confirmed as target autoantigen in PV.Ig G autoantibodies against Desmoglein3 and Desmoglein3 destruct or reduce the adhesion between cells in stratified squamous epithelium and finally lead to the PV.Genetic susceptibility is also thought to play an important role in the pathogenesis of PV.In those families which have at least one autoimmune diseases patients.First-degree relatives are more likely to have PV than second-degree relatives or third-degree relatives.HLA class II regional alleles,ST18 and other genes have been shown to be significantly related to PV,especially the HLA II regional alleles reported worldwide.Bullous Pemphigoid(BP)is the most common type in subepidermal bullous disease.The annual incidence was about 2 to 42.8 per million worldwide.The etiology and pathogenesis of PV is not entirely clear too.Autoantibodies against bullous pemphigoid antigen1 and bullous pemphigoid antigen1 in basement membrane zone lead to the deposition of Ig G and complement component C3 in epidermal basement membrane,and impair the adhesion junction was suggest to a pathogenesis of BP.Nowadays,more people believe that genetic factor also can leads to BP.HLA-DQB1*03:01,DRB1*1101,DQB1*0302 and other HLA region alleles have been confirmed as BP susceptibility genes.ABCB1,CYP2D6 genes are not located in HLA region,they are also confirmed to be associated with BP susceptibility.There are some reports on the etiology and pathogenesis of PV and BP.But the exact etiology and pathogenesis of these two diseases is still unknown,in particularly,the genetic susceptibility mechanism of these two diseases.The etiology and pathogenesis of these two diseases are urgently needed for the reason of the serious harm of these two diseases.Object: The susceptibility heritable variation of the most two common AIBDs(PV and BP)was screened and validated through GWAS study.Identify susceptibility variation in HLA region through HLA Imputation.To identify low/rare mutations those associate with PV and BP through target sequencing.We aim to build the GWAS database of PV and BP in Chinese and explore the genetic susceptibility and pathogenesis of PV and BP.Method: We generated a GWAS study to identify the susceptibility heritable variation of PV(GWAS stage: 240 cases vs.1031 control,replication stage: 252 cases vs.1852)and BP(GWAS stage: 262 cases vs.553 controls,replication stage: 420 cases vs 1788 control).We created an imputation study in HLA region using the data generate in the GWAS stage to identify susceptibility gene/loci.We carry out a target sequencing in 50 pairs of age and sex matched PV patients and controls(selected from GWAS stage used samples)to find PV associate low/rare mutation.We dected the expression of our desired gene in 40 pairs of age and sex matched PV patients and controls(selected from GWAS stage used samples).Result: 1)We updated the GWAS database of PV and BP in Chinese han.2)We identified a novel loci 11q24.1(rs11218708,Pmeta=3.1×10-8,OR=1.54)significantly associated with PV.3)UBASH3B gene which locate in 11q24.1 with significantly higher expression in PV patinents.4)We also found three new susceptbiligy loci in HLA region(HLA-DRB1*14:04(P = 2.47 × 10-38;OR = 6.28),rs7454108(P = 2.78 × 10-12;OR= 3.25)located in TAPgene and rs1051336(P= 3.06 × 10-6;OR = 0.33)locate in HLA-DRA gene)significantly associated with PV.5)We found a new suggestive susceptibility loci 1p34.2(rs1016544,Pcombine=8.72×10-7,OR=0.665)associated with BP.Conclusion: We identified 4 new susceptibility loci and 1 suggestive susceptibility lcoi in PV and BP,respectively,make the results of genetic susceptibility of these two diseases are enriched.Through GWAS research,Imputation and target sequencing method,systematically research the disease susceptibility gene/locus,and then detected the gene expression through immunohistochemistry to confirm the susceptibility gene.This study expanded our understanding of the genetic basis of PV and BP and provided new evidences and research ideas for the study of genetic pathogenesis of PV and BP.