To Study The Clinical Characteristics And Genetic Background Of Primary Nephrotic Syndrome(PNS) In Children Under Clinical Phenoomics Based On Second-Generation Sequencing(NGS)

PART Ⅰ Whole-exome sequencing of a multicenter cohort identifies genetic changes associated with clinical phenotypes in pediatric nephrotic syndromeObjective:Further exploration of the association between the genetic phenotypes and clinical phenotypes in NS of different etiologies is very critical for early clinical guidance in the formulation of the optimal diagnosis and treatment strategies.Methods:A bidirectional,multicenter cohort and large-sample study of NS based on whole-exome sequencing(WES)of samples from children enrolled from January 2010 to June 2020.The average follow-up duration for the 3 centers was 4.1-years.We present clinicopathologic and genetic information from637 pediatric NS patients.The study protocol was approved by the Ethics Committee of Children’s Hospital of Chongqing Medical University(number 2018-95)and the study was registered in the Chinese Clinical Trial Registry,China(http://www.chictr.org.cn/,Chi CTR2000029210).Results:1.A genetic disease cause was identified in 30.0% of the idiopathic steriod-resistant nephrotic syndrome(SRNS)patients.Except for in hereditary congenital nephrotic syndrome(CNS),there was no significant difference in the incidence of monogenic diseases with increasing manifestation age,but the distribution of causative genes was different.After3 months of age,the chance of identifying a genetic cause decreased to 50%between the ages of 3mo and 1 year,37.9% between 1 and 3 years,35.5%between 3 and 6 years,36.0% between 6 and 12 years,and 47.4% in those aged 12-18 years.2.The vast majority of patients with WT1 and NPHS1 mutation showed clinical signs in infancy.NPHS2 variant was the main cause of monogenic idiopathic SRNS in children aged 1-6 years old.In our study cohort,the onset age of MAGI2 and PLCE1 gene mutations mainly concentrated in the early childhood,by contrast,all patients with INF2,TRPC6,PAX2,CRB2 and AVIL mutations were over 6 years old.3.Causative mutations were detected in 39.5% of focal segmental glomerulosclerosis(FSGS)cases and 9.2% of minimal change disease(MCD)cases.4.In terms of the patterns in patients with different types of steroid resistance,the rate of a single gene mutation was 34.8% in patients with primary resistance,2.9% in patients with secondary resistance,and 71.4% in children with multidrug resistance.5.NPHS1,NPHS2 and WT1 were the most common mutation genes in our cohort,which comprising almost all monogenic CNS(n=21)and37.1%(n=26/70)idiopathic SRNS with monogenic disease.The median onset ages of NPHS1,NPHS2 and WT1 patients were 18,36,14 months respectively.NPHS2 patients had a significantly later onset age than the other two groups(P<.001 across groups).38.9%(n=7/18)of WT1 patients showed specific extrarenal involvement(sex reversal/urogenital abnormalities or tumors).Those symptoms were either present at the onset or appeared later on.Furthermore,the median renal survival time was 19 months for NPHS1,17 months for,NPHS2,11 months for WT1,WT1 patients showed a worse prognosis and progressed to ESRD more quickly(P<.001 across groups).6.Among various intensified immunosuppressive therapies,tacrolimus(TAC)showed the highest response rate,with 49.7% of idiopathic SRNS patients achieving complete remission.Idiopathic SRNS patients with monogenic disease showed similar multidrug resistance,and only 31.4% of patients with monogenic disease achieved partial remission on TAC.7.During an average 4.1-year follow-up duration,21.4% of idiopathic SRNS patients with monogenic disease progressed to end-stage renal disease(ESRD),compared with only 0.6% of patients in the genetic testing negative group.Conclusions:In summary,our data detailly described the relationship between clinical phenotypes and gene phenotypes in children with NS due to various etiology,which could be valuable in identifying monogenic disease in early stage,judging the course of disease,developing personalized treatment plans,evaluating the risk of recurrence after kidney transplantation and providing genetic counseling for these patients and their families.First,presumed steroid resistant patients showed more extrarenal involvement,syndromic features and family history,and the positive rate of single gene mutations was high.The onset age of different causative genes varied,and FSGS was the most common pathological type in idiopathic SRNS with monogenic disease.Second,we recommend genetic testing for idiopathic SRNS children,especially those with primary resistance.Third,compared with CTX and MMF,CNIs showed the highest remission rate in idiopathic SRNS.We found for the first time that the incidence of multidrug resistance in children with monogenic disease was higher,the positive rate of single gene was as high as 71.4%,and they had more rapid progression to ESRD than nonmonogenic SRNS patients.For these children,conservative treatment is recommended in clinical.PART ⅡCOMPARISON OF CLINICAL FEATURES IN CHILDREN WITH DIFFERENT DOSES OF HORMONEDEPENDENT/FREQUENCY-RELAPSING NEPHROTIC SYNDROMEObjective:Children with SDNS/FRNS were divided into GC-dependent dosedependent groups and stratified comparison of clinical,pathological and long-term prognosis was conducted to provide reference for clinical diagnosis and treatment.Methods:This part of the study included 183 children with NS who were treated in the nephrology department of our hospital and the nephrology department of 2 multi-center hospitals from January,2010 to June 30,2019,with an average follow-up time of 4.0 years.According to the "Evidence-based Guidelines for the Diagnosis and Treatment of hormone-Sensitive,Relapsing/Dependent nephrotic syndrome" formulated by the Group of Nephrology,Pediatrics Branch of the Chinese Medical Association in 2009,children with clinical manifestations of hormone-dependent/frequently relapsing nephrotic syndrome were included,and the children were grouped according to the dose of hormone dependence.Clinical pathological features,treatment response and prognosis of children with different doses of hormone dependence were compared by collecting general data,laboratory data,pathological and genetic results.Results:1.There were no significant differences in age,sex,serum albumin level,Ig G and Ig E level at the onset of disease among the three groups(P > 0.05).The pathological type of hormone-dependent children was almost micropathological type(MCD),and only 5 cases showed mesangial proliferative glomerulonephritis.In addition,no pathogenic gene mutation was found in WES of all hormone-dependent children,and no child progressed to end-stage renal disease during a mean follow-up of 4.0 years.2.In the comparison of high i OP,hormone-induced glaucoma,hormone-induced cataract,osteoporosis,specific pathogen infection and hypertension among the three groups,the high-dose hormone-dependent group was significantly higher than the medium-dose and low-dose hormone-dependent groups,and there was a statistical difference among the groups(P < 0.05).In addition,the incidence of growth disorder in hormonedependent/frequent-relapse children was higher,exceeding 25% in all three groups.Conclusions:The pathological type of SDNS/FRNS children is mainly MCD,and no clear pathogenic single gene mutation was found in the children included in this study,so early genetic detection is not recommended for these children.In addition,the long-term renal survival rate of SDNS/FRNS children is high,but long-term complications of long-term GC treatment are prominent,causing a great burden to children and their families,and more clinical attention should be paid.