Identification Of Mutations In Patients With Pure Red Cell Aplasia

Pure red cell aplasia(PRCA)is a rare hematologic disorder,which is categorized into congenital and acquired.Acquired PRCA can be further divided into idiopathic type and secondary type.Currently,secondary PRCA is considered to be associated with certain diseases such as thymoma,parvovirus B19 infection and some malignant blood diseases.However,the specific pathogenesis of idiopathic PRCA is not clear and it may be associated with autoimmune disorders.The current common treatment of idiopathic PRCA is immunosuppressive drugs such as corticosteroids and cyclosporine.Although the response is good in most patients,a relapse occurs frequently after withdrawal.Therefore,investigating the pathogenesis of PRCA in terms of DNA mutations may provide new targets for drug designing,which is necessary to improve the therapeutic efficacy and quality of life of patients with PRCA.Next-generation sequencing using a panel containing 295 critical genes was applied to detect potentially pathogenic mutations in four patients with PRCA.A total of 529 mutations were obtained after analysis.These mutations were classified into three categories,namely,uncertain(n=25),likely benign(n=20)and benign(n=484)mutations,based on the American College of Medical Genetics and Genomics(ACMG)2015 guidelines and the ClinVar database.The spatial proximity between two loci of the uncertain or benign mutations was evaluated using Hi-C datasets of 2 leukemia cell lines(KBM7 and K562),separately.Significant spatial proximity was observed in uncertain mutation pairs compared with benign mutation pairs(P=0.026 in KBM7,P=0.044 in K562).In addition,17 variants were eventually identified after excluding those with mutant frequencies >0.001,as PRCA was a rare disease and mutations with high frequencies were less likely to play an important role in the rare disease.These 17 mutations were located in 15 genes.There were two mutations in FANCF and LRP1 B genes,FANCF(R61L,I346S)and LRP1B(D3815E,A3882V),so the mutation frequencies in these 2 genes were higher than the other genes.Moreover,variant site conservative and protein structure analysis revealed that mutations in FANCF and LRP1 B genes were likely to affect protein conformation and function.This implied FANCF and LRP1 B mutations may be associated with idiopathic PRCA.Our data provided fundamental research for exploring pathogenesis of PRCA and new treatment of the disease.