Congenital nephrotic syndrome with diffuse mesangial sclerosis caused by compound heterozygous mutation in LAMA5 gene

A two-and-a-half-month-old female infant presented with generalized edema for 10 days. At presentation, she had periorbital puffiness, moderate ascites, and pedal edema. Laboratory investigations revealed serum albumin 1.3 g/dL, spot urine protein to creatinine ratio (Up:Uc) 20.87 mg/mg, total cholesterol 380 mg/dL, and serum creatinine 0.31 mg/dL. Exome sequencing revealed compound heterozygous variants in LAMA5 gene (NM_005560.6). There was a heterozygous likely pathogenic missense variant in exon 2: LAMA5: c.385C > A (depth 195 ×) and another heterozygous pathogenic variant in exon 31: LAMA5: c.3932_3936dup; parental segregation by Sanger sequencing proved that the variants were in trans. Kidney biopsy showed diffuse mesangial sclerosis (DMS). Our case adds LAMA5 gene to the constellation of genes causing DMS, in addition to the classically described WT1, LAMB2, and PLCE1 genes and to the list of genes causing congenital nephrotic syndrome (CNS).

Mutations in the NUP93, NUP107 and NUP160 genes cause steroid-resistant nephrotic syndrome in Chinese children

BACKGROUND

The variants of nucleoporins are extremely rare in hereditary steroid-resistant nephrotic syndrome (SRNS). Most of the patients carrying such variants progress to end stage kidney disease (ESKD) in their childhood. More clinical and genetic data from these patients are needed to characterize their genotype-phenotype relationships and elucidate the role of nucleoporins in SRNS.

METHODS

Four patients of SRNS carrying biallelic variants in the NUP93, NUP107 and NUP160 genes were presented. The clinical and molecular genetic characteristics of these patients were summarized, and relevant literature was reviewed.

RESULTS

All four patients in this study were female and initially presented with SRNS. The median age at the onset of the disease was 5.08 years, ranging from 1 to 10.5 years. Among the four patients, three progressed to ESKD at a median age of 7 years, ranging from 1.5 to 10.5 years, while one patient reached stage 3 chronic kidney disease (CKD3). Kidney biopsies revealed focal segmental glomerulosclerosis in three patients. Biallelic variants were detected in NUP93 in one patient, NUP107 in two patients, as well as NUP160 in one patient respectively. Among these variants, five yielded single amino acid substitutions, one led to nonsense mutation causing premature termination of NUP107 translation, one caused a single nucleotide deletion resulting in frameshift and truncation of NUP107. Furthermore, one splicing donor mutation was observed in NUP160. None of these variants had been reported previously.

CONCLUSION

This report indicates that biallelic variants in NUP93, NUP107 and NUP160 can cause severe early-onset SRNS, which rapidly progresses to ESKD. Moreover, these findings expand the spectrum of phenotypes and genotypes and highlight the importance of next-generation sequencing in elucidating the molecular basis of SRNS and allowing rational treatment for affected individuals.

A Rare De Novo Mutation in the TRIM8 Gene in a 17-Year-Old Boy with Steroid-Resistant Nephrotic Syndrome: Case Report

Idiopathic nephrotic syndrome is the most common chronic glomerular disease in children. Treatment with steroids is usually successful; however, in a small percentage of patients, steroid resistance is observed. The most frequent histologic kidney feature of steroid-resistant nephrotic syndrome (SRNS) is focal segmental glomerulosclerosis (FSGS). Genetic testing has become a valuable diagnostic tool in defining the etiology of SRNS, leading to the identification of a genetic cause. The TRIM8 gene is expressed in various tissues, including kidney cells and the central nervous system (CNS). An association between a mutation in the TRIM8 gene and an early onset of FSGS has been proposed but is not well described. We present a 17-year-old boy with epilepsy, early mild developmental delay, a low IgG serum level, and proteinuria, secondary to FSGS. A Next-Generation Sequencing (NGS)-based analysis revealed a heterozygous de novo pathogenic variant in the TRIM8 gene (c.1200C>G, p.Tyr400Ter). TRIM8 gene sequencing should be considered in individuals with early onset of FSGS, particularly accompanied by symptoms of cortical dysfunction, such as epilepsy and intellectual disability.

Copy number variation analysis in 138 families with steroid-resistant nephrotic syndrome identifies causal homozygous deletions in PLCE1 and NPHS2 in two families

BACKGROUND

Steroid-resistant nephrotic syndrome (SRNS) is the second most common cause of kidney failure in children and adults under the age of 20 years. Previously, we were able to detect by exome sequencing (ES) a known monogenic cause of SRNS in 25-30% of affected families. However, ES falls short of detecting copy number variants (CNV). Therefore, we hypothesized that causal CNVs could be detected in a large SRNS cohort.

METHODS

We performed genome-wide single nucleotide polymorphism (SNP)-based CNV analysis on a cohort of 138 SRNS families, in whom we previously did not identify a genetic cause through ES. We evaluated ES and CNV data for variants in 60 known SRNS genes and in 13 genes in which variants are known to cause a phenocopy of SRNS. We applied previously published, predefined criteria for CNV evaluation.

RESULTS

We detected a novel CNV in two genes in 2 out of 138 families (1.5%). The 9,673 bp homozygous deletion in PLCE1 and the 6,790 bp homozygous deletion in NPHS2 were confirmed across the breakpoints by PCR and Sanger sequencing.

CONCLUSIONS

We confirmed that CNV analysis can identify the genetic cause in SRNS families that remained unsolved after ES. Though the rate of detected CNVs is minor, CNV analysis can be used when there are no other genetic causes identified. Causative CNVs are less common in SRNS than in other monogenic kidney diseases, such as congenital anomalies of the kidneys and urinary tract, where the detection rate was 5.3%. A higher resolution version of the Graphical abstract is available as Supplementary information.

A novel heterozygous mutation of the NPHS1 gene in a Chinese child with congenital nephrotic syndrome: A case report

RATIONALE

Congenital nephrotic syndrome (CNS) is a heterogeneous disorder in which massive proteinuria, hypoproteinemia, and hyperlipidemia and marked edema are the main manifestations before 3 months-of-age. Here, we present a case involving the genetic diagnosis of a child with CNS.

PATIENT CONCERNS

A 31-day-old male infant with diarrhea for 25 days and generalized edema for more than 10 days. There was no family history of kidney disease. On proband whole exome sequencing, a compound heterozygous mutation of the NPHS1 gene was identified, including a novel in-frame mutation in exon 14 (c.1864_1866dupACC p. T622dup) and a missense mutation in exon 8 (c.928G>A p. D310N).

DIAGNOSES

Based on the clinical and genetic findings, this patient was finally diagnosed with CNS.

INTERVENTIONS

The main treatment options for the patient were 2-fold: anti-infective treatment and symptomatic treatment.

OUTCOMES

The patient died in follow-up 2 months later; the specific reason for death was unclear.

LESSONS

Whole exome sequencing and Sanger sequencing confirmed that the infant had CNS. Our study identified a novel mutation in an infant, thus expanding the gene-mutation spectrum of the NPHS1 gene, thus providing an efficient prenatal screening strategy and early genetic counseling.

Genetic screening in children with challenging nephrotic syndrome

Genetic screening paradigms for the nephrotic syndrome (NS) in the developed world are well established; however, screening in developing countries has received only minor attention. We retrospectively analyzed a cohort of all children who underwent genetic testing for challenging NS from our registry in the 10-year interval from 2000 to 2010 and based on 58 patients aged 0-12 years with at least one of the following clinical diagnosis: Nonsyndromic steroid-resistant nephrotic syndrome (SRNS), familial NS, and congenital NS. Of these, 23 patients (~40%) had a history of familial disease occurrence. All cases were screened for NPHS2 and WT1 mutations by direct sequencing of all exons of the genes. In addition, all patients who were diagnosed during the first three months of life were screened for NPHS1 mutations too. A genetic disease cause was identified in 12 patients (20.7%); of these, five novel mutations, all in NPHS2 accounting for 42% of all mutations and 9% of the cohort. Nine patients were found to have NPHS2 mutations. Only one case with SRNS had a mutation in WT1. Of the five congenital NS, two cases were found to have NPHS1 mutations and one case with NPHS2 mutation. Therefore, mutations in NPHS2 were the most commonly identified and explained in 15.5% of the screened patients and WT1 mutation in 1.7% of cases, whereas NPHS1 mutations were found in 40% of congenital NS cases. A genetic disease cause was identified in 20.7% of the screened patients. Among 12 identified mutations, abnormalities in NPHS2 (n = 9) were most commonly identified.

A cross-sectional nationwide survey of congenital and infantile nephrotic syndrome in Japan

BACKGROUND

Congenital nephrotic syndrome (CNS) and infantile nephrotic syndrome (INS) cause substantial morbidity and mortality. In Japan, there is a lack of knowledge regarding the characteristics of CNS and INS. This study aimed to clarify the characteristics of CNS and INS in Japan.

METHODS

This cross-sectional nationwide survey obtained data from 44 institutions in Japan managing 92 patients with CNS or INS, by means of two survey questionnaires sent by postal mail. Patients aged < 16 years by 1 April 2015, with a diagnosis of CNS or INS, were included in this study. The primary outcome was end-stage kidney disease.

RESULTS

A total of 83 patients with CNS or INS were analyzed. The most frequent disease type was non-Finnish (60.2%); 33 patients (39.8%) had Finnish type. Among those with non-Finnish-type disease, 26 had no syndrome and 24 had a syndrome, of which the most frequent was Denys-Drash syndrome (70.8%). Patients with non-Finnish-type disease with syndrome showed the earliest progression to end-stage kidney disease compared with the other two groups, whereas patients with non-Finnish-type disease without syndrome progressed more slowly compared with the other two groups. In the Finnish-type group, the disease was diagnosed the earliest; a large placenta was reported more frequently; genetic testing was more frequently performed (93.8%); mental retardation was the most frequent extra-renal symptom (21.2%); and thrombosis and infection were more frequent compared with the other groups. Patients with non-Finnish-type disease with syndrome had a higher frequency of positive extra-renal symptoms (79.2%), the most common being urogenital symptoms (54.2%). Treatment with steroids and immunosuppressants was more frequent among patients with non-Finnish-type disease without syndrome. Two patients with non-Finnish-type disease without syndrome achieved complete remission. In all groups, unilateral nephrectomy was performed more often than bilateral nephrectomy and peritoneal dialysis was the most common renal replacement therapy.

CONCLUSIONS

The present epidemiological survey sheds light on the characteristics of children with CNS and INS in Japan. A high proportion of patients underwent genetic examination, and patient management was in accord with current treatment recommendations and practices.

TRIAL REGISTRATION

Not applicable.

Asymptomatic sinusitis as an origin of infection-related glomerulonephritis manifesting steroid-resistant nephrotic syndrome: A case report

RATIONALE

Infection is a major trigger or pathogenic origin in a substantial proportion of glomerulonephritis (GN) patients, typically manifesting infection-related GN (IRGN). Various microorganisms, infection sites, and clinical and histopathological features are involved in IRGN. Once an infectious origin is identified and successfully eradicated, nephrotic syndrome or kidney dysfunction is spontaneously resolved. However, if patients are asymptomatic and the origin is undetermined, the diagnosis and treatment of GN is challenging. This case presentation reported on an IRGN case manifesting steroid-resistant nephrotic syndrome associated with asymptomatic sinusitis as a pathogenic origin.

PATIENT CONCERNS

A 68-year-old male presented with severe kidney dysfunction and edema in both extremities.

DIAGNOSIS

The patient was clinically diagnosed with hypocomplementemic nephrotic syndrome and kidney dysfunction and histopathologically with diffuse proliferative GN and a focal pattern of membranoproliferative GN. The findings suggested that idiopathic membranoproliferative glomerulonephritis type I was more likely than IRGN, given a critical lack of apparent infection.

INTERVENTIONS

Combined intravenous methylprednisolone, oral prednisolone, and cyclosporin did not improve the patient's condition. Thus, IRGN associated with inapparent infectious origin was suspected. Repeated thorough and careful examinations including CT scan showed sinusitis in his left maxillary sinus. Moreover, reanalysis of kidney specimen revealed positive nephritis-associated plasmin receptor in glomeruli, a typical finding for IRGN, supporting a pathogenic significance of his sinusitis. Medical treatment was initiated with 200 mg oral clarithromycin daily.

OUTCOMES

Oral clarithromycin gradually improved proteinuria and hypocomplementemia and resulted in nephrotic syndrome remission in parallel with opacification resolution of sinuses shown on CT.

LESSONS

This case presentation showed that asymptomatic sinusitis is potentially a pathogenic IRGN origin. A gold standard therapy for idiopathic GN, corticosteroid could be damaging in uncontrolled or underdiagnosed infection. In asymptomatic patients, a thorough screening of infectious diseases, including sinusitis, together with a renal histological evaluation of glomerular nephritis-associated plasmin receptor deposition is also essential in treating a wide spectrum of GN.

Relationships between the clinical phenotypes and genetic variants associated with the immunological mechanism in childhood idiopathic nephrotic syndrome: protocol for a prospective observational single-centre cohort study

INTRODUCTION

Idiopathic nephrotic syndrome (INS) is the most common glomerulopathy that results in childhood chronic kidney disease in China, but the relationships between different clinical phenotypes and immunological genetic variants observed in patients with INS are ambiguous and have not been well studied. A cohort study combined with whole exome sequencing might further identify the effects of immunological genetic variants on clinical phenotypes and treatment outcomes.

METHODS AND ANALYSIS

We describe a 3 year prospective observational single-centre cohort study to be conducted in the Children's Hospital of Chongqing Medical University in China. This study will recruit and investigate 336 patients with childhood-onset INS presenting with different clinical phenotypes. Whole exome sequencing will be conducted when patients progress to a confirmed clinical phenotype during follow-up. Relevant clinical and epidemiological data, as well as conventional specimens, will be collected at study entry and 1 month, 3 months, 6 months, 1 year, 2 years and 3 years after disease onset. After this cohort is generated, the immunological genetic variants of steroid-sensitive nephrotic syndrome without frequent relapse, steroid-resistant nephrotic syndrome and steroid-dependent/frequent relapse nephrotic syndrome will be evaluated.

ETHICS AND DISSEMINATION

The study protocol is approved by Ethics Committee of Children's Hospital of Chongqing Medical University (reference number 2018-140). The results will be disseminated through peer-reviewed journals and conference presentations.

TRIAL REGISTRATION NUMBER

ChiCTR1800019795.

Molecular Genetic Analysis of Steroid Resistant Nephrotic Syndrome, Detection of a Novel Mutation

INTRODUCTION

Nephrotic syndrome is a heterogeneous disease in children, with nearly 10% categorized as steroid-resistant. In this study we evaluated disease related mutations within NPHS1, NPHS2 and new potential variants in other genes.

METHODS

In the first phase of study, 25 patients with SRNS were analyzed by Sanger sequencing for NPHS1 (exon 2, 26) and all exons of NPHS2 genes. In the next step, whole exome sequencing was performed on 10 patients with no mutation in NPHS1 and NPHS2.

RESULTS

WES analysis revealed a novel mutation in FAT1 (c.10570C > A; Q3524K). We identified 4 pathogenic mutations, located in exon 4 and 5 of NPHS2 gene in 20% of patients (V180M, P118L, R168C and Leu156Phe). Also our study has contributed to the description of previously known pathogenic mutations across WT1 (R205C) and SMARCAL1 (R764Q) and a novel polymorphism in CRB2.

CONCLUSION

It seems that NPHS2, especially exons 4 and 5, should be considered as the first step in genetic evaluation of Iranian patients. We suggest conducting WES after NPHS2 screening to identify the potential genes associated with SRNS, Further studies are required to examine more common genes in the first step and then designing native laboratory panels.

A Systematic Analysis of Major Susceptible Genes in Childhood-onset Steroid-resistant Nephrotic Syndrome

AIM

Nephrotic syndrome is a urinary disease, causing high morbidity and mortality. However, the mutation prevalence of major susceptible genes in childhood-onset steroid-resistant nephrotic syndrome (SRNS) in China is limited. In this study, we performed a systematic analysis of the mutations in 18 major SRNS-susceptible genes in Chinese SRNS children.

METHODS

Mutation analysis was performed to sequence 18 major SRNS-susceptible genes (NPHS1, NPHS2, CD2AP, PLCE1, ACTN4, TRPC6, INF2, WT1, LMX1B, LAMB2, LAMB3, GLA, ITGB4, SCARB2, COQ2, PDSS2, MTTL1, and SMARCAL1) using a PCR-based MassArray technology in 38 childhood-onset SRNS patients in China. This cohort included 10 sporadic cases and 28 familial cases from 7 SRNS families with disease onset between the ages of 1-13 years.

RESULTS

Our analysis detected a heterozygous missense mutation (p.E447K, pathogenic) in NPHS1 in 3/28 familial patients (10.7%) and 1/10 (10.0%) patient without a family history. In addition, two NPHS2 mutations (p.R138X and p.R291W, pathogenic) were identified in 2 patients from another family (7.1% familial cases, 0% sporadic cases, 5.2% overall). Pathogenic mutations of remaining 16 SRNS-susceptible genes were not detected.

CONCLUSION

Our results have verified the significant prevalence of pathogenic NPHS1 and NPHS2 mutations in childhood-onset SRNS in China, while the other 16 SRNS-susceptible genes seem to have lesser contribution to child-onset SRNS. Therefore, our study indicates that it is very necessary to make more efforts to target NPHS1 and NPHS2 for childhood-onset SRNS treatment, especially in China.

Infants with congenital nephrotic syndrome have comparable outcomes to infants with other renal diseases

BACKGROUND

Children with congenital nephrotic syndrome (CNS) commonly develop end stage renal failure in infancy and require dialysis, but little is known about the complications and outcomes of dialysis in these children.

METHODS

We conducted a retrospective case note review across members of the European Society for Pediatric Nephrology Dialysis Working Group to evaluate dialysis management, complications of dialysis, and outcomes in children with CNS.

RESULTS

Eighty children (50% male) with CNS were identified form 17 centers over a 6-year period. Chronic dialysis was started in 44 (55%) children at a median age of 8 (interquartile range 4-14) months. Of these, 17 (39%) were on dialysis by the age of 6 months, 30 (68%) by 1 year, and 40 (91%) by 2 years. Peritoneal dialysis (PD) was the modality of choice in 93%, but 34% switched to hemodialysis (HD), largely due to catheter malfunction (n = 5) or peritonitis (n = 4). The peritonitis rate was 0.77 per patient-year. Weight and height SDS remained static after 6 months on dialysis. In the overall cohort, at final follow-up, 29 children were transplanted, 18 were still on dialysis (15 PD, 3 HD), 19 were in pre-dialysis chronic kidney disease (CKD), and there were 14 deaths (8 on dialysis). Median time on chronic dialysis until transplantation was 9 (6-18) months, and the median age at transplantation was 22 (14-28) months.

CONCLUSIONS

Infants with CNS on dialysis have a comparable mortality, peritonitis rate, growth, and time to transplantation as infants with other primary renal diseases reported in international registry data.

Characterization of a novel disease-associated mutation within NPHS1 and its effects on nephrin phosphorylation and signaling

Mutations in the transmembrane protein nephrin (encoded by NPHS1) underlie nearly half of all cases of congenital nephrotic syndrome (CNS), which is caused by aberrations in the blood filtering function of glomerular podocytes. Nephrin directly contributes to the structure of the filtration barrier, and it also serves as a signaling scaffold in podocytes, undergoing tyrosine phosphorylation on its cytoplasmic tail to recruit intracellular effector proteins. Nephrin phosphorylation is lost in several human and experimental models of glomerular disease, and genetic studies have confirmed its importance in maintenance of the filtration barrier. To date, however, the effect of CNS-associated NPHS1 variants on nephrin phosphorylation remains to be determined, which hampers genotype-phenotype correlations. Here, we have characterized a novel nephrin sequence variant, A419T, which is expressed along with C623F in a patient presenting with CNS. Nephrin localization is altered in kidney biopsies, and we further demonstrate reduced surface expression and ER retention of A419T and C623F in cultured cells. Moreover, we show that both mutations impair nephrin tyrosine phosphorylation, and they exert dominant negative effects on wildtype nephrin signaling. Our findings thus reveal that missense mutations in the nephrin extracellular region can impact nephrin signaling, and they uncover a potential pathomechanism to explain the spectrum of clinical severity seen with mild NPHS1 mutations.

Whole Exome Sequencing of Patients with Steroid-Resistant Nephrotic Syndrome

BACKGROUND AND OBJECTIVES

Steroid-resistant nephrotic syndrome overwhelmingly progresses to ESRD. More than 30 monogenic genes have been identified to cause steroid-resistant nephrotic syndrome. We previously detected causative mutations using targeted panel sequencing in 30% of patients with steroid-resistant nephrotic syndrome. Panel sequencing has a number of limitations when compared with whole exome sequencing. We employed whole exome sequencing to detect monogenic causes of steroid-resistant nephrotic syndrome in an international cohort of 300 families.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Three hundred thirty-five individuals with steroid-resistant nephrotic syndrome from 300 families were recruited from April of 1998 to June of 2016. Age of onset was restricted to <25 years of age. Exome data were evaluated for 33 known monogenic steroid-resistant nephrotic syndrome genes.

RESULTS

In 74 of 300 families (25%), we identified a causative mutation in one of 20 genes known to cause steroid-resistant nephrotic syndrome. In 11 families (3.7%), we detected a mutation in a gene that causes a phenocopy of steroid-resistant nephrotic syndrome. This is consistent with our previously published identification of mutations using a panel approach. We detected a causative mutation in a known steroid-resistant nephrotic syndrome gene in 38% of consanguineous families and in 13% of nonconsanguineous families, and 48% of children with congenital nephrotic syndrome. A total of 68 different mutations were detected in 20 of 33 steroid-resistant nephrotic syndrome genes. Fifteen of these mutations were novel. NPHS1, PLCE1, NPHS2, and SMARCAL1 were the most common genes in which we detected a mutation. In another 28% of families, we detected mutations in one or more candidate genes for steroid-resistant nephrotic syndrome.

CONCLUSIONS

Whole exome sequencing is a sensitive approach toward diagnosis of monogenic causes of steroid-resistant nephrotic syndrome. A molecular genetic diagnosis of steroid-resistant nephrotic syndrome may have important consequences for the management of treatment and kidney transplantation in steroid-resistant nephrotic syndrome.

Efficacy and Safety of Rituximab in Children With Steroid- and Cyclosporine-resistant and Steroid- and Cyclosporine-dependent Nephrotic Syndrome

INTRODUCTION

There is evidence of the effectiveness of rituximab in treatment of nephrotic syndrome in children. The present study aimed to assess safety and the therapeutic effectiveness of rituximab in steroid- and cyclosporine-resistant pediatric nephrotic syndrome.

MATERIALS AND METHODS

Forty-three children with steroid- and cyclosporine-resistant or steroid- and cyclosporine-dependent noncongenital nephrotic syndrome were included in the study to receive intravenous rituximab, 375 mg/m2/wk, for 4 weeks. The children were followed up for 2 years. Effectiveness was defined as remission of proteinuria in response to rituximab. Side effects of rituximab were monitored.

RESULTS

Overall, 23 (57.1%) of the children had steroid- and cyclosporine-resistant nephrotic syndrome, of whom 8 (34.8%) revealed complete response and 3 (13%) revealed partial response. Seven children (16.7%) had late-resistant nephrotic syndrome, of whom 6 (85.7%) revealed complete response and none revealed partial response. Ten children (26.2%) had steroid- and cyclosporine-dependence all of whom revealed complete response to rituximab. Complete response rate was significantly higher in those with drug-dependent pattern than the other groups (P = .002). There was no association between response to rituximab and pathological basis of disease. Side effects were found in 4 patients as leukopenia in 2, alopecia in 1, and eosinophilia in 1.

CONCLUSIONS

Rituximab is effective for children with nephrotic syndrome with high efficacy and well tolerability, especially in those with steroid- and cyclosporine-dependent nephrotic syndrome.

Cytokine Gene Polymorphism in Children With Idiopathic Nephrotic Syndrome

INTRODUCTION

Idiopathic nephrotic syndrome (INS) is a glomerular disease with completely unclear pathogenesis and different responses to steroid therapy. This study aimed to investigate the role of cytokine genes promoter polymorphisms in steroid therapy responses.

MATERIALS AND METHODS

One hundred children with INS and 30 healthy controls were studied. Genotyping of TNF-α-G308A single nucleotide polymorphism was done using polymerase chain reaction-restriction fragment length polymorphism method, while of IL-6-G174C single nucleotide polymorphism was done using real-time polymerase chain reaction.

RESULTS

The IL-6-G174C exhibited a significantly different genotype distribution among the children with INS compared with the controls (GG versus CC, P = .02; GG versus GC, P = .003; odds ratio [OR], 5.83; 95% confidence interval [CI], 1.64 to 20.70; as well as alleles distribution of G versus C, P ? .001; OR, 7.57; 95% CI, 2.28 to 25.17). With regard to TNF-α-G308A genotype, there was no significant difference in genotype distribution of the children with INS compared with the controls, but a significant difference was observed at the alleles level. Comparing the steroid-resistant group with the steroid-sensitive group, significant association was found at genotypic level in case of IL-6-G174C (GG versus CC, P = .03; OR, 5.52; 95% CI, 1.39 to 21.89), but no association was found regarding GG versus GC. At the allelic level of IL-6-G174C, there was no significant association either.

CONCLUSIONS

IL-6-G174C and TNFα-G308A polymorphisms may affect susceptibility to idiopathic nephrotic syndrome and might affect steroid response in INS patients.

Long-Term Outcome of Steroid-Resistant Nephrotic Syndrome in Children

We investigated the value of genetic, histopathologic, and early treatment response information in prognosing long-term renal outcome in children with primary steroid-resistant nephrotic syndrome. From the PodoNet Registry, we obtained longitudinal clinical information for 1354 patients (disease onset at >3 months and <20 years of age): 612 had documented responsiveness to intensified immunosuppression (IIS), 1155 had kidney biopsy results, and 212 had an established genetic diagnosis. We assessed risk factors for ESRD using multivariate Cox regression models. Complete and partial remission of proteinuria within 12 months of disease onset occurred in 24.5% and 16.5% of children, respectively, with the highest remission rates achieved with calcineurin inhibitor-based protocols. Ten-year ESRD-free survival rates were 43%, 94%, and 72% in children with IIS resistance, complete remission, and partial remission, respectively; 27% in children with a genetic diagnosis; and 79% and 52% in children with histopathologic findings of minimal change glomerulopathy and FSGS, respectively. Five-year ESRD-free survival rate was 21% for diffuse mesangial sclerosis. IIS responsiveness, presence of a genetic diagnosis, and FSGS or diffuse mesangial sclerosis on initial biopsy as well as age, serum albumin concentration, and CKD stage at onset affected ESRD risk. Our findings suggest that responsiveness to initial IIS and detection of a hereditary podocytopathy are prognostic indicators of favorable and poor long-term outcome, respectively, in children with steroid-resistant nephrotic syndrome. Children with multidrug-resistant sporadic disease show better renal survival than those with genetic disease. Furthermore, histopathologic findings may retain prognostic relevance when a genetic diagnosis is established.

Childhood idiopathic steroid-resistant nephrotic syndrome at a Single Center in Khartoum

Prevalence, clinicopathological features, and outcome of childhood idiopathic steroid-resistant nephrotic syndrome (ISRNS) vary in different countries. We report on these parameters in a single center in Khartoum. We retrospectively reviewed all the records of children with idiopathic nephrotic syndrome (INS) followed up in the pediatric renal unit, Soba Hospital, Khartoum between 2001 and 2012. ISRNS was defined as no remission within four weeks of daily prednisolone at a dose of 60 mg/m2. In 430 children with INS 130 (28%) had SRNS with a mean age of 7.7 ± 4.12 years. Males were 78 (60%). At presentation, hematuria was recorded in 57%, hypertension was recorded in 48%, and renal impairment in 15%. Histopathology showed focal segmental glomerulosclerosis in 40.8%, mesangioproliferative glomerulonephritis (22.3%), mesangiocapillary glomerulonephritis (16.9%), minimal change disease (MCD) (16.2%), and membranous glomerulonephritis (3.8%). Therapy included cyclosporine in 38.5%, additional therapy with cyclophosphamide, mycophenolate mofetil or tacrolimus in 20.8%, and steroids ± diuretics ± angiotensin converting enzyme (ACE) inhibitors in 40.7%. After 3.64 ± 2.84 years, 26.8% had complete remission (CR), 18.6% partial remission (PR), 26.8% were unremitting, 21.5% had chronic kidney disease (CKD), 1.6% died, and 4.6% were lost to follow-up. Non-MCD cases had significantly lower CR and higher CKD rates than MCD (P = 0.047 and 0.041, respectively). Cyclosporine ± additional therapy was significantly associated with higher rate of CR than steroids ± ACE inhibitors ± diuretics (P = 0.001), but the prevalence of CKD between the two groups was not significantly different (P = 0.604). Impaired renal function and hypertension at presentation were risk factors for CKD (P = 0.001 and 0.001, respectively). In Sudanese children with ISRNS, non-MCD lesions were the most common lesions. This pattern in addition to the lack of adequate therapy may explain the relatively lower CR and higher CKD rates. Impaired renal function and hypertension at presentation were risk factors for progression to CKD.

Reduced INF2 expression in nephrotic syndrome is possibly related to clinical severity of steroid resistance in children

AIM

Mutations of the inverted formin 2 gene (INF2), which encodes a member of the formin family, cause autosomal dominant focal segmental glomerulosclerosis (FSGS) and Charcot-Marie-Tooth (CMT) disease-associated FSGS. However, their role in idiopathic FSGS remains unclear. This study investigated INF2 localization in the normal adult kidney and its expression in children with idiopathic nephrotic syndrome.

METHODS

We generated a rabbit polyclonal antibody against the conjugated peptide from human INF2 and studied the glomerular expression of INF2 and synaptopodin using normal human adult kidney tissues and tissues from children with glomerular diseases such as minimal change disease (MCD), FSGS, IgA nephropathy (IgAN), non-IgA mesangial proliferative glomerulonephritis (non-IgAN), and Henoch-Schönlein purpura nephritis (HSPN).

RESULTS

The anti-INF2 antibody detected an approximately 140-kD fragment isolated from adult mature glomeruli by western blotting. Immunohistochemically, INF2 was detected in podocytes and renal arteries. Among 56 patients, INF2 in glomeruli was expressed at a similar level in patients with MCD, IgAN, non-IgAN, or HSPN and controls. In FSGS patients, INF2 expression in glomeruli was either decreased or absent. There was a relationship between decreased INF2 expression and the clinical severity of steroid resistant nephrotic syndrome (SRNS).

CONCLUSION

We propose that examination of INF2 expression may help to differentiate MCD from FSGS and evaluate the clinical severity of SRNS in children.

Steroid Resistant Nephrotic Syndrome-Genetic Consideration

Nephrotic syndrome is defined as the association of massive proteinuria, hypoalbuminaemia, edema, and hyperlipidemia. It is separated to steroid-sensitive or steroid-resistant (SRNS) forms in respect to the response to intensive steroid therapy. SRNS usually progresses to end-stage renal failure. According to the North American Pediatric Renal Trials and Collaborative Studies SRNS constitutes the second most frequent cause of ESRD in the first two decades of life. Unfortunately, there is no curative treatment for majority of patients. Majority of the SRNS patients have the histologic picture of focal segmental glomerulosclerosis. Interestingly, the risk of recurrence in the kidney graft in patients with hereditary SRNS is lower than in those who do not have genetic background. The etiology and pathogenesis of SRSN has remained enigma for decades. The discovery of 39 dominant or recessive SRNS genes enabled better understanding of the function of the glomerular podocytes and slit membrane. Hildebrandt's group has shown that 85% of the SRNS cases with onset by 3 months of age and 66% with onset by 1 year of age can be explained by recessive mutations in one of four genes only (NPHS1, NPHS2, LAMB2, or WT1). The same group used modern diagnostic techniques such as the next generation sequencing and tested a large international cohort of SRNS patients (n = 1783 families). The diagnostic panel included 21 genes with a recessive mode of inheritance and 6 genes with a dominant mode of inheritance. Single-gene cause was detected in 29.5% (526 of 1783) of the families with SRNS that manifested before 25 years of age. The identification of causative single-gene mutations may have important therapeutic consequences in some cases. This is very important for patients who carry mutations in a gene of coenzyme Q10 biosynthesis (COQ2, COQ6, ADCK4, or PDSS2). In these patients the treatment with coenzyme Q10 may be indicated. Also, patients with recessive mutations in PLCE1 may respond fully to the treatment with steroids or cyclosporine A. The patients with CUBN may benefit the treatment with vitamin B12. The detection of causative mutations may also be very important for familial genetic counseling and for prenatal diagnosis.

Childhood Idiopathic Steroid Resistant Nephrotic Syndrome, Different Drugs And Outcome

BACKGROUND

The management of steroid resistant nephrotic syndrome (SRNS) is quite difficult in paediatric patients. Not only the remission is difficult but also these patients are at risk of progression to end stage renal disease (ESRD). The goal of treatment is either to achieve complete remission or even partial remission as it is the most important predictor of disease outcome.

METHODS

This study was conducted at The Children's Hospital, Lahore from February 2014 to May 2015. The SRNS patients of either sex between ages of 1-12 years were included with histology showing mesangioproliferative glomerulonephritis (MesangioPGN), focal segmental glomerulosclerosis (FSGS) or minimal change disease (MCD). Patients were given different immunosuppressant drugs and steroid 30 mg/m2 alternate day therapy on case to case basis and kept on regular follow up to check for response and adverse effects.

RESULTS

Total of 105 patients included, 63 (60%) male and 42 (40%) female patients. The age ranges from 1.08 to 12 years, mean age of 6.53 years and SD of ±3.17. Tacrolimus was the most common drug used 43 (41%) patients followed by cyclosporine in 38 (36.2%) patients, while Mycophenolate mofetil (MMF) was prescribed in 21 (20%) patients. Complete response was in 96 (91.4%) initially while partial response was seen in 8 (7.6%) patients. On follow up, 92 (87.6%) patients showed complete response and partial response was in 5 (4.7%) patients. Cushingoid features and hypertrichosis were the most common adverse effect seen.

CONCLUSIONS

Steroid resistant nephrotic syndrome can be managed well with various immunosuppressant drugs and steroids but treatment should be individualized according to clinical presentation, disease histology and cost/social factors.

[Nutritional management of kidney diseases in children]

The prevalence of various kidney diseases in children remains high in recent decades. Adequate nutrition management can enhance the effectiveness of drug treatment, slow the frequency of relapses andprevent the progression of the disease. The article is devoted to modern approaches to diet therapy in various kidney diseases in children with the defeat of tubular and glomerular appa ratus. For the first time the therapeutic diets for children with various kidney diseases are presented. Particular attention is paid to diet therapy in nephrotic syndrome (steroid-responsive and steroid-refractory). Dietary approaches with modern formulas for enteral nutrition in cases of steroid therapy complications in children with renal insufficiency (in predialysis stage and on dialysis) are described. Differentiated nutritional approaches for patients with different types of crystalluria are separately presented.

Dealing with the incidental finding of secondary variants by the example of SRNS patients undergoing targeted next-generation sequencing

BACKGROUND

Steroid-resistant nephrotic syndrome (SRNS) is a severe cause of progressive renal disease. Genetic forms of SRNS can present with autosomal recessive or autosomal dominant inheritance. Recent studies have identified mutations in multiple podocyte genes responsible for SRNS. Improved sequencing methods (next-generation sequencing, NGS) now promise rapid mutational testing of SRNS genes.

METHODS

In the present study, a simultaneous screening of ten SRNS genes in 37 SRNS patients was performed by NGS.

RESULTS

In 38 % of the patients, causative mutations in one SRNS gene were found. In 22 % of the patients, in addition to these mutations, a secondary variant in a different gene was identified.

CONCLUSIONS

This high incidence of accumulating sequence variants was unexpected but, although they might have modifier effects, the pathogenic potential of these additional sequence variants seems unclear so far. The example of molecular diagnostics by NGS in SRNS patients shows that these new sequencing technologies might provide further insight into molecular pathogenicity in genetic disorders but will also generate results, which will be difficult to interpret and complicate genetic counseling. Although NGS promises more frequent identification of disease-causing mutations, the identification of causative mutations, the interpretation of incidental findings and possible pitfalls might pose problems, which hopefully will decrease by further experience and elucidation of molecular interactions.

Biallelic Mutations in Nuclear Pore Complex Subunit NUP107 Cause Early-Childhood-Onset Steroid-Resistant Nephrotic Syndrome

The nuclear pore complex (NPC) is a huge protein complex embedded in the nuclear envelope. It has central functions in nucleocytoplasmic transport, nuclear framework, and gene regulation. Nucleoporin 107 kDa (NUP107) is a component of the NPC central scaffold and is an essential protein in all eukaryotic cells. Here, we report on biallelic NUP107 mutations in nine affected individuals who are from five unrelated families and show early-onset steroid-resistant nephrotic syndrome (SRNS). These individuals have pathologically focal segmental glomerulosclerosis, a condition that leads to end-stage renal disease with high frequency. NUP107 is ubiquitously expressed, including in glomerular podocytes. Three of four NUP107 mutations detected in the affected individuals hamper NUP107 binding to NUP133 (nucleoporin 133 kDa) and NUP107 incorporation into NPCs in vitro. Zebrafish with nup107 knockdown generated by morpholino oligonucleotides displayed hypoplastic glomerulus structures and abnormal podocyte foot processes, thereby mimicking the pathological changes seen in the kidneys of the SRNS individuals with NUP107 mutations. Considering the unique properties of the podocyte (highly differentiated foot-process architecture and slit membrane and the inability to regenerate), we propose a "podocyte-injury model" as the pathomechanism for SRNS due to biallelic NUP107 mutations.

A single-gene cause in 29.5% of cases of steroid-resistant nephrotic syndrome

Steroid-resistant nephrotic syndrome (SRNS) is the second most frequent cause of ESRD in the first two decades of life. Effective treatment is lacking. First insights into disease mechanisms came from identification of single-gene causes of SRNS. However, the frequency of single-gene causation and its age distribution in large cohorts are unknown. We performed exon sequencing of NPHS2 and WT1 for 1783 unrelated, international families with SRNS. We then examined all patients by microfluidic multiplex PCR and next-generation sequencing for all 27 genes known to cause SRNS if mutated. We detected a single-gene cause in 29.5% (526 of 1783) of families with SRNS that manifested before 25 years of age. The fraction of families in whom a single-gene cause was identified inversely correlated with age of onset. Within clinically relevant age groups, the fraction of families with detection of the single-gene cause was as follows: onset in the first 3 months of life (69.4%), between 4 and 12 months old (49.7%), between 1 and 6 years old (25.3%), between 7 and 12 years old (17.8%), and between 13 and 18 years old (10.8%). For PLCE1, specific mutations correlated with age of onset. Notably, 1% of individuals carried mutations in genes that function within the coenzyme Q10 biosynthesis pathway, suggesting that SRNS may be treatable in these individuals. Our study results should facilitate molecular genetic diagnostics of SRNS, etiologic classification for therapeutic studies, generation of genotype-phenotype correlations, and the identification of individuals in whom a targeted treatment for SRNS may be available.

Spectrum of steroid-resistant and congenital nephrotic syndrome in children: the PodoNet registry cohort

BACKGROUND AND OBJECTIVES

Steroid-resistant nephrotic syndrome is a rare kidney disease involving either immune-mediated or genetic alterations of podocyte structure and function. The rare nature, heterogeneity, and slow evolution of the disorder are major obstacles to systematic genotype-phenotype, intervention, and outcome studies, hampering the development of evidence-based diagnostic and therapeutic concepts. To overcome these limitations, the PodoNet Consortium has created an international registry for congenital nephrotic syndrome and childhood-onset steroid-resistant nephrotic syndrome.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Since August of 2009, clinical, biochemical, genetic, and histopathologic information was collected both retrospectively and prospectively from 1655 patients with childhood-onset steroid-resistant nephrotic syndrome, congenital nephrotic syndrome, or persistent subnephrotic proteinuria of likely genetic origin at 67 centers in 21 countries through an online portal.

RESULTS

Steroid-resistant nephrotic syndrome manifested in the first 5 years of life in 64% of the patients. Congenital nephrotic syndrome accounted for 6% of all patients. Extrarenal abnormalities were reported in 17% of patients. The most common histopathologic diagnoses were FSGS (56%), minimal change nephropathy (21%), and mesangioproliferative GN (12%). Mutation screening was performed in 1174 patients, and a genetic disease cause was identified in 23.6% of the screened patients. Among 14 genes with reported mutations, abnormalities in NPHS2 (n=138), WT1 (n=48), and NPHS1 (n=41) were most commonly identified. The proportion of patients with a genetic disease cause decreased with increasing manifestation age: from 66% in congenital nephrotic syndrome to 15%-16% in schoolchildren and adolescents. Among various intensified immunosuppressive therapy protocols, calcineurin inhibitors and rituximab yielded consistently high response rates, with 40%-45% of patients achieving complete remission. Confirmation of a genetic diagnosis but not the histopathologic disease type was strongly predictive of intensified immunosuppressive therapy responsiveness. Post-transplant disease recurrence was noted in 25.8% of patients without compared with 4.5% (n=4) of patients with a genetic diagnosis.

CONCLUSIONS

The PodoNet cohort may serve as a source of reference for future clinical and genetic research in this rare but significant kidney disease.

Immunosupressive therapy in children with steroid-resistant nephrotic syndrome: single center experience

INTRODUCTION

[corrected] Nephrotic syndrome is one of the most frequent glomerular diseases among children, and steroid therapy remains as the treatment choice. In spite of this, 10 to 15% of the patients are steroidresistant, and the best therapy for such cases has never been defined. Mycophenolate acid (MA) is one of the treatments used in such situations.

OBJECTIVE

To describe the clinical behavior of children diagnosed with steroid-resistant nephrotic syndrome (SRNS) and to assess the therapeutic response to MA.

METHODS

This was a retrospective and descriptive study.

RESULTS

26 clinical records of patients with SRNS; 70% male and 30% female. All patients underwent kidney biopsies, which showed a predominance of focal segmental glomerulosclerosis (FSGS). The immunosuppresive drugs used were: Mycophenolate mofetil (MMF) 100%, Cyclosporine 69.2%, Cyclophosphamide 23.1%, and Rituximab 23%. One month after treatment initiation with MMF 61.5% achieved remission. The median of relapses per year for the patients was 3 (p25: 2.75 - p75: 4). This median became 1 (p25: 1 - p75: 3.25) after using this medication (p = 0.08). Furthermore, prior to the start of the MMF treatment, the median of the steroid dose was 1 (p25: 0.5- p75: 1.62) mg/k/day. After using MMF, this median became 0.07 (p25: 0 - p75: 0.55) mg/k/day (p < 0.001), in 8 patients prednisolone was stopped.

CONCLUSION

In our experience, treatment with MMF showed positive results such as decrease in the frequency of relapses, less proteinuria, and reduction in the dose of steroids administered without deterioration of glomerular filtration rates. However, more studies are needed to assess efficacy, safety, and optimal dosage.

Steroid-resistant idiopathic nephrotic syndrome in children: long-term follow-up and risk factors for end-stage renal disease

INTRODUTION

Steroid resistant idiopathic nephrotic syndrome (SRINS) in children is one of the leading causes of progression to chronic kidney disease stage V (CKD V)/end stage renal disease (ESRD).

OBJECTIVE

The aim of this retrospective study is to evaluate the efficacy of immunosuppressive drugs (IS) and to identify risk factors for progression to ESRD in this population.

METHODS

Clinical and biochemical variables at presentation, early or late steroid resistance, histological pattern and response to cyclosporine A (CsA) and cyclophosfamide (CP) were reviewed in 136 children with SRINS. The analyzed outcome was the progression to ESRD. Univariate as well as multivariate Cox-regression analysis were performed.

RESULTS

Median age at onset was 5.54 years (0.67-17.22) and median follow up time was 6.1 years (0.25-30.83). Early steroid-resistance was observed in 114 patients and late resistance in 22. Resistance to CP and CsA was 62.9% and 35% respectively. At last follow-up 57 patients reached ESRD. The renal survival rate was 71.5%, 58.4%, 55.3%, 35.6% and 28.5% at 5, 10, 15, 20 and 25 years respectively. Univariate analysis demonstrated that older age at onset, early steroid-resistance, hematuria, hypertension, focal segmental glomerulosclerosis (FSGS), and resistance to IS were risk factors for ESRD. The Cox proportional-hazards regression identified CsAresistance and FSGS as the only predictors for ESRD.

CONCLUSION

Our findings showed that CsA-resistance and FSGS were risk factors for ESRD.

[Multicenter study on present status of diagnosis and treatment of steroid-resistant nephrotic syndrome in children]

OBJECTIVE

To investigate the treatment of multi-center hospitalized children with steroid resistant nephrotic syndrome (SRNS) retrospectively.

METHOD

The Subspecialty Group of Nephrology, The Society of Pediatrics, Chinese Medical Association organized 35 hospitals to investigate children with primary SRNS from 2008 to 2011. By filling in the questionnaire, data including age, gender, clinical type, related examination, pathology and treatment in local hospitals were collected, and then statistical analysis was performed.

RESULT

A total of 35 hospitals participated in this survey, 577 patients were enrolled, their age was from 8 months to 18 years. The male to female ratio was 2: 1. School-age children accounted for 33.3% (n = 194). Clinical types were mostly simple nephrotic syndrome, which accounted for 60.5% (n = 349) and nephritis nephrotic syndrome accounted for 39.5% ( n = 228). The incidences of different types of NS were significantly different between 2008 and 2011 (χ(2) = 10.751, P = 0.001). There were 306 cases of infants who received renal biopsy. Renal pathology showed that 40 of them had mesangial proliferative glomerulonephritis (MsPNG), 17 focal segmental glomerulo- sclerosis (FSGS), 9 membranous nephropathy (MN), 9 minimal change disease (MCD), 8 minor lesions, 3 endocapillary proliferative glomerulonephritis (EnPGN) , 2 membrano-proliferative glomerulonephritis (MPGN), 2 sclerotic glomerulonephritis and 2 podocyte lesions in 2008. Otherwise there were 53 MsPGN, 35 FSGS, 25 minor lesions, 23 MCD, 13 MN, 5 MPGN, 3 podocyte lesions, 2 EnPGN, 1 sclerotic glomerulonephritis. Since the evidence-based guidelines had been issued in 2011, 209 cases were treated with adequate-dose prednisone therapy > 4 weeks program. Eighty-seven children with nephrotic syndrome whose urinary protein could not be turned negative after 4 weeks' glucocorticoid treatment were treated with high-dose methylprednisolone for 1 course. Thirty-eight of these children got negative urinary protein after the pulse therapy. Tacrolimus and cyclosporine treatment of SRNS significantly increased compared with 2008 (19.5% vs. 9.1% and 29.0% vs. 22.1% respectively). The most commonly used immunosuppressant was cyclophosphamide pulse therapy (56.5% vs. 58.1%). The situation of SRNS children with immunosuppression in two years was not statistically significant (χ(2) = 10.027, P > 0.05).

CONCLUSION

This study presented the current status of the diagnosis and treatment of SRNS of children in China. For children with nephrotic syndrome whose urinary protein cannot be turned negative after 4 weeks' glucocorticoid treatment, the best choice is to provide them with high-dose methylprednisolone pulse treatment for 1 course. Currently the treatment of SRNS diversifies, in which hormones and immunosuppressants are the main choices, and cyclophosphamide pulse therapy is still the preferred choice. However, according to different renal pathological types and different indications, choice of immunosuppressants remains to be further studied and standardized.

[Mutational analysis of MYO1E in children with sporadic steroid-resistant nephrotic syndrome in Chinese Han ethnic group]

OBJECTIVE

Previous studies have demonstrated that two homozygous missense MYO1E mutations are associated with childhood autosomal recessive focal segmental glomerulosclerosis in steroid-resistant nephrotic syndrome (SRNS) families from Italy and Turkey. Non-disease-causing heterozygous MYO1E variants were also found in other SRNS patient cohorts. However, the role of MYO1E mutations in Chinese sporadic SRNS has not been established.

METHOD

Peripheral blood samples were collected for genetic analysis from 54 children with sporadic SRNS in Chinese Han ethnic group and a normal control group of 59 healthy adult volunteers. None of the patients carried mutations in NPHS2 or WT1. Genomic DNA was extracted from peripheral blood leukocytes. Twenty-eight exons and exon-intron boundaries of the MYO1E gene were amplified by polymerase chain reaction. Mutational analysis was performed by direct DNA sequencing and restriction endonuclease digestion.

RESULT

Fifty-one variants in the MYO1E gene were identified in 54 children with sporadic SRNS. Among them, 10 MYO1E mutations of IVS1-11T>C, IVS2-86T>A, 279T>C (D93D), IVS6-181G>A, 718C>T (L240F), 1678A>G (T560A), IVS16-35A>G, IVS18+48T>A, IVS19+38G>A and IVS25+13C>T were detected in 11 patients, whereas they were absent in the 59 normal Chinese controls. Forty-one variants in MYO1E were identified and all of them were published in single nucleotide polymorphism database from national center for biotechnology information. Furthermore, all the 10 MYO1E mutations were in heterozygous states.

CONCLUSION

MYO1E mutations are not a major cause of Chinese children with sporadic SRNS in the study.

Posterior reversible encephalopathy syndrome in a child with steroid-resistant nephrotic syndrome: a case report and review of literature

Posterior reversible encephalopathy syndrome (PRES) is a rare and serious syndrome of central nervous system that can develop in both adults and children. It is characterized by acute onset of headache, confusion, seizures or focal neurological deficits along with radiological findings of white matter abnormalities in the parietal and occipital lobes. In the past ten years, this syndrome has been described mainly in adults, rare in children. Here, we report a case of PRES presenting in a 12-year-old girl with steroid-resistant nephrotic syndrome. Her neurological symptom was rapidly recovered after control of hypertension without discontinuation of cyclosporine A.

Genotype-phenotype associations in WT1 glomerulopathy

WT1 mutations cause a wide spectrum of renal and extrarenal manifestations. Here we evaluated disease prevalence, phenotype spectrum, and genotype-phenotype correlations of 61 patients with WT1-related steroid-resistant nephrotic syndrome relative to 700 WT1-negative patients, all with steroid-resistant nephrotic syndrome. WT1 patients more frequently presented with chronic kidney disease and hypertension at diagnosis and exhibited more rapid disease progression. Focal segmental glomerulosclerosis was equally prevalent in both cohorts, but diffuse mesangial sclerosis was largely specific for WT1 disease and was present in 34% of cases. Sex reversal and/or urogenital abnormalities (52%), Wilms tumor (38%), and gonadoblastoma (5%) were almost exclusive to WT1 disease. Missense substitutions affecting DNA-binding residues were associated with diffuse mesangial sclerosis (74%), early steroid-resistant nephrotic syndrome onset, and rapid progression to ESRD. Truncating mutations conferred the highest Wilms tumor risk (78%) but typically late-onset steroid-resistant nephrotic syndrome. Intronic (KTS) mutations were most likely to present as isolated steroid-resistant nephrotic syndrome (37%) with a median onset at an age of 4.5 years, focal segmental glomerulosclerosis on biopsy, and slow progression (median ESRD age 13.6 years). Thus, there is a wide range of expressivity, solid genotype-phenotype associations, and a high risk and significance of extrarenal complications in WT1-associated nephropathy. We suggest that all children with steroid-resistant nephrotic syndrome undergo WT1 gene screening.

[Mutational analysis of MYO1E in Chinese children with familial steroid-resistant nephrotic syndrome]

OBJECTIVE

Steroid-resistant nephrotic syndrome (SRNS) with MYO1E mutations has been identified as autosomal recessive focal segmental glomerulosclerosis (FSGS). To date, only two homozygous mutations in the MYO1E gene were reported in three families with FSGS. This study aimed to examine mutations in the MYO1E gene in children with familial SRNS in the Han Chinese ethnic group.

METHODS

Between 2005 and 2010, peripheral blood samples were collected from the probands, their siblings and parents of four families with autosomal recessive SRNS in the Han Chinese ethnic group. Four probands were studied from nine patients. The mutational analysis of MYO1E was performed by polymerase chain reaction and direct DNA sequencing. Fifty-nine healthy volunteers with normal urine analysis were included as controls.

RESULTS

Twenty-five MYO1E variants in the prohands from 4 families with SRNS were identified in this study. Among them, 24 variants were found in NCBI dbSNP. One heterozygous mutation IVS21-85G>A was found in the prohand from Family D, whereas it was absent in 59 normal Chinese controls. No splice site change caused by IVS21-85G>A was reported by analysis with NetGene2.

CONCLUSIONS

MYO1E mutations are not a major cause of Chinese familial SRNS in this study.

[Recent advances in the research on mechanisms underlying podocyte-specific gene mutation-related steroid-resistant nephrotic syndrome]

Steroid-resistant nephrotic syndrome poses a significant clinical challenge. Its pathogenesis has not been fully elucidated. In recent years, numerous studies have shown that podocyte-specific gene mutations may play important roles in the development of steroid-resistant nephrotic syndrome. Among the identified genes mutated in podocytes include NPHS2, NPHS1, WT1, TRPC6, MDR1, PLCE1, LMX1B, and LAMB2. This review aims to summarize the characteristics of these mutated genes in podocytes. The putative role for these podocyte-specific mutated genes in the pathogenesis, diagnosis, treatment and prognosis of steroid-resistant nephrotic syndrome is also discussed.

R229Q polymorphism of NPHS2 gene in patients with late-onset steroid-resistance nephrotic syndrome: a preliminary study

INTRODUCTION

Depending on the response to standard steroid therapy, nephrotic syndrome it is classified to steroid-sensitive and steroid-resistant nephrotic syndrome (SRNS). Mutations in several genes including NPHS2 have been implicated in SRNS. Gene R229Q polymorphism (p.R229Q) of NPHS2 is associated with adolescent- or adult-onset SRNS in European and South American populations. We investigated this polymorphism among a group of Iranian-Azeri patients with primary SRNS.

MATERIALS AND METHODS

All participants had the primary late-onset form of focal segmental glomerulosclerosis (FSGS) and their clinical feature was steroid unresponsiveness. They were compared with a group of age- and sex-matched individuals without any renal disease for NPHS2 gene as controls. The R229Q polymorphism (p.R229Q) was investigated in the case and control groups.

RESULTS

A total of 25 patients (mean age, 26.6 +/- 8.0 years) with primary FSGS and 35 controls (mean age, 26.0 +/- 8.7 years) were studied. Serum creatinine of patients and their 24-hour protein excretion at the time of study were 2.4 +/- 1.94 mg/dL and 2830 +/- 981 mg/dL, respectively. Molecular study showed no p.R229Q polymorphism, neither in patients nor in controls.

CONCLUSIONS

In this preliminary study, we showed that NPHS2 gene p.R229Q polymorphism does not present in Iranian-Azeri population with SRNS. Larger studies are needed to confirm our results and other mutated genes should also be considered in these patients.

NPHS2 gene in steroid-resistant nephrotic syndrome: prevalence, clinical course, and mutational spectrum in South-West Iranian children

INTRODUCTION

Mutations in podocin (NPHS2) gene have the key role in the pathogenesis of steroid-resistant nephrotic syndrome (SRNS) in children, but data is scarce regarding their prevalence and natural course among different all ethnic groups. This study was aimed to demonstrate the spectrum of NPHS2 mutations in children with SRNS and to compare the clinical course of disease in patients with and without mutation.

MATERIALS AND METHODS

All 8 exons of NPHS2 were sequenced in 99 children, including 49 with SRNS and 50 with steroid-sensitive nephrotic syndrome (control group) by DNA sequencing.

RESULTS

The prevalence rates of NPHS2 gene mutation among children with SRNS and SSNS were 31% and 4%, respectively. The prevalence rates of mutation among familial and sporadic forms were 57% and 26%, respectively. Thirty-three percent of the children experienced recurrence of primary disease after kidney transplantation, none of whom had a mutation. The clinical response to treatment was poorer in children with mutation in comparison with patients without mutation (12% versus 32%, respectively; odds ratio, 3.29, 95% confidence interval, 0.40 to 25.64). Patients with and without mutation could not be differentiated by demographic and histological features, glomerular filtration rate at onset, hypertension, progression to end-stage renal disease, and proteinuria.

CONCLUSIONS

Mutations of NPHS2 gene are frequent among Iranian children with SRNS. Regarding similar clinical features in patients with and without mutation and poor response to pharmacotherapy in patients with mutation, a molecular approach might be necessary for different treatment plans and prediction of prognosis.

Treatment outcome of late steroid-resistant nephrotic syndrome: a study by the Midwest Pediatric Nephrology Consortium

BACKGROUND

Idiopathic nephrotic syndrome (NS) in children is classified as steroid sensitive or steroid resistant. Steroid sensitivity typically portends a low risk of permanent renal failure. However, some initially steroid-sensitive patients later develop steroid resistance. These patients with late steroid resistance (LSR) are often treated with immunosuppressant medications, but the effect of these additional drugs on the long-term prognosis of LSR is still unknown.

METHODS

A retrospective chart review was performed on patients diagnosed with idiopathic NS and subsequent LSR during the 8-year study period from 2002 up to and including 2009, with a minimum of 2 years of follow-up. Primary outcome measures were proteinuria and renal function.

RESULTS

A total of 29 patients were classified as having LSRNS. The majority of patients received treatment with calcineurin inhibitors and/or mycophenolate mofetil. Seven patients received three or more non-steroid immunosuppressant medications. Sustained complete or partial remission was achieved in 69 % of patients. Three developed end-stage renal disease, and all others maintained normal renal function. There were 13 episodes of serious adverse events, none of which were fatal or irreversible.

CONCLUSION

Most patients with LSRNS responded to immunosuppressive therapy by reduction or resolution of proteinuria and preservation of renal function. The results suggest that immunosuppressive treatment is a viable option in NS patients who develop LSR.

Congenital nephrotic syndrome—a treatable cause

A 27-day-old infant from a tribal area presented with congenital nephrotic syndrome (CNS). The presence of clinical features of syphilis, proven syphilis in the mother and complete recovery following penicillin therapy confirmed a diagnosis of congenital syphilis. In developing countries, treatable causes of CNS such as syphilis need to be considered in infants presenting with nephrotic syndrome.

Genetic screening in adolescents with steroid-resistant nephrotic syndrome

Genetic screening paradigms for congenital and infantile nephrotic syndrome are well established; however, screening in adolescents has received only minor attention. To help rectify this, we analyzed an unselected adolescent cohort of the international PodoNet registry to develop a rational screening approach based on 227 patients with nonsyndromic steroid-resistant nephrotic syndrome aged 10-20 years. Of these, 21% had a positive family history. Autosomal dominant cases were screened for WT1, TRPC6, ACTN4, and INF2 mutations. All other patients had the NPHS2 gene screened, and WT1 was tested in sporadic cases. In addition, 40 sporadic cases had the entire coding region of INF2 tested. Of the autosomal recessive and the sporadic cases, 13 and 6%, respectively, were found to have podocin-associated nephrotic syndrome, and 56% of them were compound heterozygous for the nonneutral p.R229Q polymorphism. Four percent of the sporadic and 10% of the autosomal dominant cases had a mutation in WT1. Pathogenic INF2 mutations were found in 20% of the dominant but none of the sporadic cases. In a large cohort of adolescents including both familial and sporadic disease, NPHS2 mutations explained about 7% and WT1 4% of cases, whereas INF2 proved relevant only in autosomal dominant familial disease. Thus, screening of the entire coding sequence of NPHS2 and exons 8-9 of WT1 appears to be the most rational and cost-effective screening approach in sporadic juvenile steroid-resistant nephrotic syndrome.

Hearing status in children with frequently relapsing and steroid resistant nephrotic syndrome

BACKGROUND

Children with idiopathic nephrotic syndrome (INS) are at risk of hearing impairment due to nephrotoxic drugs and biochemical impairments.

METHODS

Forty children with INS aged 5-16 years [20 patients with frequently relapsing nephrotic syndrome (FRNS)/steroid dependent nephrotic syndrome (SDNS) and 20 with steroid resistant nephrotic syndrome (SRNS)] and 20 normal healthy controls were enrolled in this study. Pure tone audiometry was done using the ALPS AD 2000 audiometer. Sensorineural hearing loss was diagnosed when the bone conduction level was >20 dB and the difference in air to bone gap was ≤15 dB. Based on the air conduction (AC) threshold, deafness was graded into the following categories: mild (26-40 dB), moderate (41-55 dB), moderately severe (56-70 dB), severe (71-91 dB) and profound (>91 dB).

RESULTS

Children with FRNS/SDNS had a higher threshold for hearing at frequencies of 250 and 500 Hz, respectively, than the controls. Of the children in the FRNS/SDNS category, three (15 %) had mild sensorineural hearing impairment. These children had a low serum calcium level (P < 0.03) and received higher cumulative doses of furosemide (P < 0.04). Children with SRNS had a higher threshold for hearing at frequencies of 250, 500, 1,000, and 2,000 Hz, respectively, than the controls. Of the 20 children with SRNS, ten (50 %) had sensoineural hearing impairment (8 mild, 2 moderate). Children with SRNS with a hearing defect had received a higher cumulative dose of furosemide (P < 0.03).

CONCLUSIONS

Children with FRNS/SDNS and SRNS are at risk of sensorineural hearing impairment. The risk factors associated with this impairment were higher cumulative doses of furosemide and hypocalcemia. Larger prospective cohort studies are required to evaluate this association.

Histopathologic and clinical findings of congenital nephrotic syndrome in Iranian children: a study of two centers

INTRODUCTION

Congenital nephrotic syndrome (CNS), an uncommon form of kidney disease, presents during the first year of life and is a diagnostic and therapeutic challenge for the pediatricians as well as pediatric nephrologists. Our study is the first study of Iranian children with CNS in two pediatric nephrology centers in Tehran, Iran.

MATERIALS AND METHODS

We reviewed medical charts of 30 infants diagnosed with CNS from 1990 to 2005.

RESULTS

There were 15 boys and 15 girls with CNS (mean age, 1.7 months). The presentation of the disease was nephrotic syndrome in 96.6% of the patients. Eighty percent of the patients presented within 3 months of life and 16 in the neonatal period. The Finnish type of CNS was seen in 43.3% and diffuse mesangial sclerosis in 50%. Preterm labor and low birth weight was seen in 20%. A family history of nephrotic syndrome in infancy was noted for 8 children (26.7%). Numerous complications of nephrotic syndrome occurred in 73.3%. Seventy percent of the patients had 27 episodes of infections. Sepsis was seen in 43.3% of the children, of which 61.5% were caused by gram-negative bacteria and 38.6% were caused by Staphylococcus aureus. Thrombotic complications and hypertension developed in 6.6% and 23.3% of the patients, respectively. The mortality rate of patients was 86.6%.

CONCLUSIONS

Diffuse mesangial sclerosis is an important cause of CNS. The outcome of our patients was poor and most of our patients died before reaching the age of 5 years old.

Mycophenolate mofetil for treatment of idiopathic nephrotic syndrome in children

INTRODUCTION

Management of frequently relapsing steroid-responsive or steroid-resistant idiopathic nephrotic syndrome (NS) in children has been a clinical challenge for pediatric nephrologists. In addition, adverse effects of long-term corticosteroids and cyclosporine administration emerge seeking a safe and effective treatment. The purpose of this study was to evaluate the safety and efficacy of mycophenolate mofetil (MMF) in these patients.

MATERIALS AND METHODS

This study reviewed the outcomes of children with frequently relapsing or steroid-resistant idiopathic NS who were treated with MMF.

RESULTS

A total of 36 patients (23 boys and 13 girls) were included. Their mean age at the time of diagnosis of NS was 61.94 ± 43.9 months. Of the children, 91.6% of those who had frequent relapses and 8.3% of those with steroid-resistant NS responded to MMF significantly (P < .001), with no significant association between age and gender with response to MMF. The treatment was well tolerated with no significant complications.

CONCLUSIONS

In children with frequently relapsing NS, MMF was a safe and useful drug for maintaining remission, while it was of low value in children with steroid-resistant NS.

[Correlation between Chinese medicine syndromes and the NPHS1 gene and NPHS2 gene polymorphism as well as corticosteroid sensitivity in patients with minimal change disease]

OBJECTIVE

To explore the correlation between Chinese medicine (CM) syndromes and the NPHS1 gene and NPHS2 gene polymorphism as well as corticosteroid sensitivity in patients with minimal change disease (MCD).

METHODS

A total of 94 MCD patients were recruited, including 58 steroid-sensitive nephritic syndrome (SSNS) patients and 36 steroid-resistant nephritic syndrome (SRNS) patients. Genomic DNA was obtained from peripheral blood lymphocytes and sequence analysis of single nucleotide polymorphisms (SNPs) in the genes was performed.

RESULTS

(1) The SNPs of G349A-3 in NPHS1 gene was found in MCD, but the SNPs of G686A-5 and C695T-5 in NPHS2 gene were not discovered in MCD. (2) When comparing the frequency of genotype AA and allele A in NPHS1 gene (G349A-3), genotype AA and allele A were higher in the SRNS group than in the SSNS group (P < 0.05). (3) When compared with the SRNS group, qi yang deficiency syndrome had a higher incidence in the SSNS group, and yin deficiency syndrome and qi-yin deficiency syndrome had a less incidence in the SSNS, but with no statistical difference (P > 0.05). The rheumatism syndrome had a higher incidence in the SSNS group (P < 0.05). The blood stasis syndrome had a lower incidence in the SSNS with statistical difference (P < 0.05). (4) There was no statistical difference in the correlation between GG, AA, GA and CM syndromes (P > 0.05).

CONCLUSIONS

Homozygous mutations of AA and allele A in NPHS1 gene were correlated to SRNS patients of MCD. Rheumatism syndrome patients were prone to be sensitive to corticosteroids, while patients of blood stasis syndrome were prone to be insensitive to corticosteroids. We didn't discover the correlation between NPHS1 gene polymorphism and CM syndrome distribution.